THE IMPACT OF SCHOOL START TIMES ON ADOLESCENT HEALTH AND
ACADEMIC PERFORMANCE
Introduction In the early 1990s, a team of researchers lead by
Brown Universitys Mary Carskadon determined that circadian biology
drives the delayed sleep-wake patterns of adolescents. (1) Pubertys
onset marks the beginning of a phase shift, with adolescents going
to bed later and rising later than younger children. (2, 3, 4)
Typically adolescents are unable to fall asleep at earlier times
and sleep in later to get the 9 (5) hours of sleep they need. (2,
3, 6, 7, 8, 9) In 1994, physicians began advising school leaders to
eliminat[e] early starting hours for teenagers[.] (10) Sleep
experts urge a delay in morning classes until 8:30 a.m., or later,
for middle and high school students. (2, 11, 12, 13, 14, 15) Few
administrators have listened, (12) instead adhering to school
schedules described by preeminent scientists as abusive, (16)
nonsense, (17) deleterious, (18) cruel, (19) and nuts. (20) Most
U.S. high schools schedule classes during the 7 oclock hour, (12,
21, 22, 23) while melatonin still pressures adolescents to sleep.
(3, 24) The vast majority of teenagers attending early starting
schools meet the morning bell in a sleep-deprived state. (2, 6, 8,
12, 23, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
The consequences of this sleep deprivation are severe, impacting
adolescents physical and mental health, as well as daytime
functioning. (40) Students at later starting schools get more
sleep, (4, 13, 30, 37, 41, 42, 43) perform better academically,
(13, 24, 44, 45) have significantly fewer automobile accidents,
(31, 46) report greater motivation (41) and less depression, (3,
37, 41, 47) experience fewer physical health difficulties, (37, 41)
are less likely to be tardy or truant, (2, 30, 41, 44, 47, 48)
demonstrate better performance in attention level, impulsivity, and
rate of performance[,] (13) and, according to Brookings Institute
economists, will likely earn significantly more money as adults
when school begins at roughly 9 a.m. (49) Policymakers may
eventually decide when the school day begins. (50, 51) Until then,
at least during the school year, adolescent sleep sufficiency, a
point of concern for the CDC (18, 26, 52, 53, 54) and the National
Institutes of Health, (55, 56, 57) will substantially be determined
by the whims of local school boards. (58)
This paper is updated weekly here --
http://schoolstarttime.org/; a three-page summary is available here
(pdf).
I.
The Prevalence of Restricted Weeknight Sleep Among
Adolescents
Almost all teenagers in this country are sleep-deprived.
(99)---Maida Chen, M.D., Assistant Professor of Pediatrics,
University of Washington School of Medicine, Assistant Director,
Pediatric Sleep Disorders Center, Seattle Childrens Hospital. The
great majority of high school students are getting insufficient
sleep. (25, 26, 27, 100, 101) The 2011 National Sleep Foundation
poll found only 14% of teenagers between the ages of 13 and 18
report getting nine or more hours of sleep on weeknights. (25) A
2010 study published in the Journal of Adolescent Health found that
nationwide, on an average school night, 68.9% of students reported
insufficient sleep (9). (26) The 2007 Youth Risk Behavior Survey of
the Centers for Disease Control and Prevention (CDC) found that on
weeknights, 31.1% of U.S. students reported getting 8 or more hours
of sleep; 42% of ninth graders did so versus only 22% of 12th
graders. (100) The 2006 National Sleep Foundation poll found only
one in five adolescents get the recommended 9 hours of sleep per
night. (101) Studies have shown sleep deficiency on school nights
as prevalent for the better part of the last three decades.
Researchers comparing data from 1981 and 20032006 found that bed
times and wake times were similar, with teens averaging 8-8 hours
sleep on school nights. (28) In a 1994 survey of high school
students, 26% reported sleeping less than 6.5 hours on school
nights, while only 15% reported sleeping 8.5 hours or longer. (55)
In 2002, teenagers averaged 7.5 hours sleep on school nights, with
a quarter of them getting only 6.5 hours per night. (102)
Scientists writing in the June 2005 issue of Pediatrics observed,
Both shortterm and long-term strategies that address the epidemic
of sleep deprivation among adolescents will be necessary to improve
health and maximize school performance. (6) In 2008, Norwalk
Hospital sleep experts noted that the pattern of rising sleep debt
during the week followed by weekend catch-up still leaves most
teens sleep-deprived by an estimated 10 hours sleep per week. (2)
In 2009, researchers again commented, Sleep deprivation among
adolescents is epidemic. (103) Sleep scientists have uniformly
concluded, Sleep deprivation among adolescents appears to be, in
some respects, the norm rather than the exception in contemporary
society. (27) Because of a multitude of intrinsic and environmental
factors, adolescents are particularly vulnerable to disturbed
sleep, and are one of the most sleep deprived age groups in the
country. (40) It has been shown that adolescents increased
sleepiness is similar to the clinical level of sleepiness presented
by patients with severe sleep disorders. (104)
2
Multiple factors contribute to sleep deficiency in teens,
including electronic devices, jobs, erratic sleep schedules,
caffeine, social and school obligations. (21, 29, 105, 106, 107,
108) Restricted sleep, however, is primarily limited to school
nights, rather than weekend nights, with students losing up to 2
hours of sleep after the start of school. (2, 6, 21, 22, 26, 28,
29, 30, 55, 102, 109, 110) The consequences of this sleep
deprivation are severe, impacting adolescents physical and mental
health, as well as daytime functioning. (40) Sleep deficiency in
adolescents is associated with: profoundly impaired learning
capacity, memory, and alertness (11, 21, 27, 29, 111, 112, 113,114,
115, 116, 117)
depression, anxiety, fatigue (29, 118, 119) increased risk of
suicidal ideation and completed suicide (53, 120, 121, 122, 123,
124) increased frequency of automobile accidents (31, 46) decreased
athletic and motor skills (125, 126) excessive weight gain (127,
128, 129, 130) increased likelihood of risk-taking behaviors,
including drug or alcohol use (53, 131, 132) increased likelihood
of criminal conduct (133) physical, psychological, or social
difficulties (134, 135, 136) elevated blood pressure (137)
interference with secondary brain development, (138, 139) etc.
These findings generally appear to apply equally to young adults,
(24, 40, 136, 140) and, with the obvious exception of driving
accidents, to middle school children as well. (22, 23, 30, 44) In
light of these myriad negative effects on adolescent health and
well-being, the identification of potentially modifiable factors
that escalate the risk of insufficient sleep in this population is
an important public health issue. (41) The vast majority of
adolescents do not get enough sleep. Research has shown that the
average teenager needs 9 to 9 hours of sleep a night. This is not
all that much less than school-aged children need. However, the
average amount of sleep that teenagers get is about 7 hours on
school nights. Even on weekends and holidays, when they try to
catch-up, teenagers average just 9 hours of sleep. This leads to
teenagers missing an average of 2 hours of sleep per night, and it
accumulates over time. (Mindell & Owens, Clinical Guide to
Pediatric Sleep: Diagnosis and Management of Sleep Problems
(Lippincott Williams & Wilkins, 2nd ed. 2010) p. 258.) This two
hour discrepancy between weekend and school-night sleep has caused
researchers to consider the relationship between pedagogical
structures and adolescent biology. (2, 5, 6, 21, 23, 24, 26, 30,
31, 41, 44, 46, 101, 115, 116, 131, 138, 141)
3
II.
The Basics of Adolescent Sleep Biology
Sending kids to school at 7 a.m. is the equivalent of sending an
adult to work at 4 in the morning. (179) ---William Dement, M.D.,
Sc.D., Ph.D., Professor of Psychiatry and Behavioral Sciences,
Stanford University School of Medicine, Division Chief, Stanford
University Division of Sleep. In todays society, persevering
through tiredness is often considered a badge of honour. (180)
Functioning while sleep deprived shows the ability to endure
hardship. (181) Historically, many members of the military view
sleep as an indulgence; sleep deprivation in the interest of duty
is even revered. (182) Diminished sleep, however, is a stressor
which may adversely affect the morale or psychological well-being
of even highly-trained military personnel. (183) Adolescents
represent a population far more vulnerable to the effects of
restricted sleep. (2, 5, 6, 21, 29, 40, 53, 55, 107, 131) Most
adolescents rise between 5 a.m. and 6:30 a.m. to meet the morning
school bell, essential training, some believe, for the real world.
(184) While many adults in the real world start work early, many
start considerably later than the average high school student.
Recent census data reflect that roughly 30 percent of adults begin
their morning commute after 8:00 a.m. (185) College students may
get underway even later. In the Fall of 2010, for example, fewer
than 2 percent of undergraduate courses at the University of
Michigan started at 8:00 a.m. or earlier, and roughly 85 percent of
classes started at 9:30 a.m. or later. (49) Until reaching the age
of majority, adolescents are judged as too young to vote, sit as
jurors, or join the armed forces, but old enough to rise while much
of the world is still sleeping.(25)
The hour when the school day begins is the factor with the
biggest impact on adolescent sleep sufficiency, (28) a point seldom
considered by those preparing students for the real world. (12)
Professor of Neurology and Director of the Minnesota Regional Sleep
Disorders Center, Mark Mahowald, explains: All of the research that
has been done shows that older adolescents need more sleep than
younger ones. They fall asleep later and wake up later to get the
sleep they need. Despite these two facts, almost all districts
start the senior high schools first. Were sending them to school
during the last one-third of their sleep cycles. Its comparable to
adults getting up at 3 a.m. or 4 a.m. You wouldnt want to be making
important decisions at that hour. I think its nuts. The sleep
deficit builds up until they fall asleep at school or driving. (20,
italics added.) In adults, shift work desynchronizes sleep cycles,
resulting in sleep loss, and, in some instances, serious adverse
health consequences. (186, 187, 188) Sleep cycle disruption, a
feature of early school start times, and the attendant
restricted4
sleep, (20, 23) are similarly closely associated with serious
health-risk consequences among adolescents, except that these
individuals are still developing, (2) their mortality/morbidity is
increasingly implicated, (31, 46, 53, 120) and learningostensibly
the primary purpose of educationis diminished. (2, 11, 13) While
younger adolescents (i.e., middle school children) may be less
likely than secondary school students to draw an early start time,
(1, 121) those who do experience outcomes similar to those found
among their older peers. (13, 23, 30, 44) As will be discussed,
there are at least three significant biological factors to consider
when evaluating the confluence of start times and adolescent sleep
requirements: the essential/restorative value of sleep, (189, 190)
adolescent circadian timing, (1, 103, 191) and the increased
susceptibility in this population to the negative effects of sleep
loss. (2, 5, 6, 21, 29, 40, 53, 55, 107, 131, 192) A. Sleep
Needs/Sleep Loss as a Stressor Sleep is vital to your well-being,
as important as the air you breathe, the water you drink and the
food you eat. (219)---Nelson L. Turcios, M.D., Pediatric
Pulmonologist. Animal studies have demonstrated that sleep properly
belongs in Maslows hierarchy of physiological needs as
indispensable to survival. (189, 190) Sleep is not some biological
luxury. (220) Sleep is biologically obligatory. (5) Animals
deprived of sleep die.(189, 220)
For adolescents, the National Sleep Foundation defines sleep as
insufficient if 9 hours per night. (26) Carskadon and Wolfson point
to ~9.2 hours of sleep as optimal and ~8.5 hours as adequate for
this population. (12) Older adolescents require 9-10 hours. (2)
Early sleep research suggested that after birth, sleep requirements
declined during childhood development, leveling off at eight hours
during puberty. (2) Research over the past thirty years, however,
has demonstrated that the number of sleep hours required during the
explosion of growth and other body changes of puberty remains at
nine hours or more throughout adolescence. (2) Mere rest does not
create the restorative state of having slept. [] The fundamental
difference between sleep and a deeply relaxed wakefulness is that
sleep involves dropping into a state with a relative loss of
awareness of and responsiveness to the external world. This state
of unresponsiveness appears to be necessary for the restorative
processes that occur during sleep to take place. (220) Sleep helps
to restore both mind and body. The bodys engines are able to slow
down and cool off when we sleep, decreasing the metabolic
processes, heart rate, respiration, digestion, and body
temperature. Sleep can also be a time of increased healing or, in
children, a time of accelerated growth. (Abaci, Take Charge of
Your5
Chronic Pain: The Latest Research, Cutting-Edge Tools (Globe
Pequot Press 2010) p. 241, n. omitted.) Deep sleep coincides with
the release of growth hormone in children and young adults. (190)
[S]leep seems to be particularly important during periods of brain
maturation. (Across species, maturing individuals sleep more than
fully mature individuals.) (220) [A]dolescent sleep systems appear
to become more vulnerable to stress at a time when social turmoil
and difficulties are often increasing. (220) Restricted sleep and
interrupted circadian timing, discussed infra, serve as
environmental/physiological stressors in humans. (183, 221, Wise,
Hopkin, & Garland, Handbook of Aviation Human Factors (CRC
Press 2nd ed. 2009) p. 18-3.) Sleep loss means sustaining
wakefulness longer, which stresses the body, leading to additional
problems. (222) Prenatal development, infancy, childhood and
adolescence are times of increased vulnerability to stressors. The
presence of stressors during these critical periods can have
prolonged effects, such as sustained cacostasis [defective
homeostasis, dyshomeostasis, distress] that can last the entire
lifetime of an individual. (223) B. Adolescent Circadian Timing All
life on earth has evolved under a rhythmically changing cycle of
light and darkness, and organisms from single-celled bacteria up to
man possess an internal representation of time. These 24 hour
cycles, termed circadian rhythms, persist in the absence of
external cues, and provide a means of anticipating changes in the
environment rather than passively responding to them. In mammals,
including man, light provides the critical input to the circadian
system, synchronising the body clock to prevailing conditions.
(248)---Russell Foster, Ph.D., F.R.S., Chair of Circadian
Neuroscience, Oxford University [circadian: circa = about; die =
day]. Although sleep/wake patterns have long been known to delay in
adolescents, behavioral factors (e.g., jobs, social diversions,
scholastic obligations) were assumed to be entirely responsible.
(21, 191) Terman and Hocking in 1913, for example, noted a shift
from vesperal to matinal sleeping during adolescence, attributing
the change to increasing homework. (21) In the 1970s, researchers
recognized that sleep patterns change fundamentally at the
transition to adolescence. (5) Adolescence commences at pubertys
onset; (2) i.e., when children attain Tanner stage 2 (sexual
maturation rating). (250, Stang & Story, Adolescent Growth and
Development, publish. in, Guidelines for Adolescent Nutrition
Services (Stang & Story, edits., Univ. Minn. 2005) p. 1.) The
normal age range of pubertal onset is between 8 and 13 years in
girls and between 9 years 6 months and 13 years, 6 months in boys.
(249) The timing and tempo of puberty vary widely, even among
healthy children. (250) Adolescence concludes at about 19.5 years
in girls and 20.9 years in boys. (7, 103)
6
In 1993, Carskadon and colleagues determined that the circadian
system undergoes developmental biological changes when puberty
arrives. (1, 191) Other researchers have made similar observations,
together providing converg[ing] evidence that the circadian phase
undergoes a delay in association with puberty[.] (Carskadon,
Maturation of processes regulating sleep in adolescents, publish.
in, Sleep in Children: Developmental Changes in Sleep Patterns
(Marcus, Carroll, & Donnelly eds., Informa Healthcare, 2nd ed.
2008) p. 100.) Growing evidence supports the conjecture that
endogenous circadian period and light sensitivity of the circadian
system are altered during puberty in humans and animals. Such
changes could explain the development of delayed sleep phase during
puberty. (103) Recent studies demonstrate adolescent changes in
sleep (delayed sleep phase and disrupted sleep) are evident prior
to the bodily changes associated with puberty. (Wolfson &
Richards, Young Adolescents: Struggles with Insufficient Sleep,
publish. in, Sleep and Development (Oxford Univ. Press., El Sheikh
edit. 2011) p. 268, citations omitted.) Young people have special
needs during adolescent development that are related directly to
their intrinsic sleep cycles. (6) The sleep pressure rate, or
homeostatic drivethe biological trigger that causes sleepinessslows
down in adolescence. (26, 103) Adolescents develop a resistance to
sleep pressure that permits them to stay up later. (103) At the
same time, their circadian phase becomes relatively delayed, which
provides them with a drive to stay awake later in the evening and
to sleep later in the morning. (103) The magnitude of the delay is
greater on nonschool days. (21) Additionally, rising time on
nonschool days also gets later as adolescence progresses. (21) The
preferred sleep onset time for most adolescents is 11 p.m. or
later. (2, 7, 8, 9) Bedtime gets later on school and nonschool days
with increasing adolescent age. (21, 191) The circadian system and
melatonin, a sleep-inducing hormone, direct a sleep cycle in teens
which operates from approximately 11 p.m. to 8 a.m. (2, 3, 6, 7, 8,
9) The pubertal stage correlates with the circadian phase marker
such that more mature children show a later phase of melatonin
secretion offset. (21, Carskadon, Maturation of processes
regulating sleep in adolescents, publish. in, Sleep in Children:
Developmental Changes in Sleep Patterns (Marcus, Carroll, &
Donnelly eds., Informa Healthcare, 2nd ed. 2008) p. 100 [the
presence of melatonin may be measured in salivary levels].)
Melatonin continues in peak production until 7 a.m., then stops at
8 a.m. (24) In adults, levels peak at 4 a.m. Therefore, waking a
teenager at 7 a.m. is equivalent to waking up an adult at 4 a.m.
(20, 24) According to Stanford sleep expert Dr. William Dement,
adolescents biological rhythms are set in such a way that they
really cant wake up earlier. Its like telling a person they have to
jump eight feet. They just cant.(184)
7
Many parents and teachers become frustrated that adolescents
seem to create their own problem of not getting enough sleep by
choosing a late bedtime, despite their complaints of sleepiness in
the morning. However, there are multiple factors that contribute to
later bedtimes, and it is increasingly clear that adolescents stay
awake later largely for biological, not social, reasons. As with
adults, the physiological factor that most powerfully regulates the
timing of waking and sleeping in adolescents is the circadian
rhythm, a hard-wired clock in the suprachiasmatic nucleus of the
brain. (2) Phase delayed sleep/wake patterns prevail among
adolescents globally. (251, 252, 253, 254, 255, 256, 257) [A] delay
in the timing of sleep during the second decade of life has been
observed in over 16 countries on 6 continents, in cultures ranging
from pre-industrial to modern. (103) Forced awakening does not
appear to reset the circadian rhythm. (Wahlstrom, Accommodating the
Sleep Patterns of Adolescents Within Current Educational
Structures: An Uncharted Path, publish. in, Adolescent Sleep
Patterns, Biological, Social, and Psychological Influences
(Carskadon, edit., Cambridge Univ. Press 2002) p. 174, ns.
omitted.) Scientists have repeatedly observed that adhering to Poor
Richards judgment Early to bed, early to risemay be difficult in
the presence of a biologically driven phase preference. (1, 7, 32)
Light/Technology Exposure Nearly all adolescents in the U.S. have
at least one electronic item such as a television, computer,
telephone, or music device in their bedrooms. (25, 105) The
brightness of a television or computer screen may interfere with
melatonin release, because release occurs only under dark
conditions. (105) In turn, regulation of the sleep-wake cycle may
be disturbed. (105) Electronic device multitasking appears to be a
good predictor of diminished sleep. (105) Video gaming may be
particularly disruptive to adolescent sleep.(108)
As little as five hours exposure to normal levels of indoor
lighting, and not just very bright light, can reset the human
biological clock, a finding which indicates that many people in
industrialized countries may be constantly sleep deprived and in a
permanent state of jet lag. (280) A study of Brazilian adolescents
living without electricity showed a delay in sleep, however, those
living in nearby electrified homes delayed sleep to a greater
degree and slept less. (Carskadon, Maturation of processes
regulating sleep in adolescents, publish. in, Sleep in Children:
Developmental Changes in Sleep Patterns, supra, p. 96.)
8
Although light treatments have served to modify circadian timing
in some populations, a 2005 study reported early morning light
treatments did not change adolescent sleep/wake cycles or improve
daytime performance during weekdays. (6) By contrast, carefully
controlling light exposure, including wearing eyeshades to exclude
evening light, has been successful in modifying adolescent
circadian timing. (8) However, this approach may be less than
practical for most adolescents. Inadequate exposure to
short-wavelength (blue) light further delays the adolescent
sleep/wake cycle, pushing back the onset of melatonin by about six
minutes for each morning light-deprived day. (281) According to
Mariana Figueiro, Ph.D., Assistant Professor and Program Director
at Rensselaer Polytechnic Institutes Lighting Research Center, As
teenagers spend more time indoors, they miss out on essential
morning light needed to stimulate the bodys 24-hour biological
system, which regulates the sleep/wake cycle[.] (282) The problem
is that todays middle and high schools have rigid schedules
requiring teenagers to be in school very early in the morning.
These students are likely to miss the morning light because they
are often traveling to and arriving at school before the sun is up
or as its just rising. This disrupts the connection between daily
biological rhythms, called circadian rhythms, and the earths
natural 24-hour light/dark cycle, explains Figueiro. (282) In
addition, the schools are not likely providing adequate electric
light or daylight to stimulate this biological or circadian system,
which regulates body temperature, alertness, appetite, hormones and
sleep patterns. Our biological system responds to light much
differently than our visual system. It is much more sensitive to
blue light. Therefore, having enough light in the classroom to read
and study does not guarantee that there is sufficient light to
stimulate our biological system. (282) The situation in schools can
be changed rapidly by the conscious delivery of daylight (e.g., via
large windows/skylights), (283) which is saturated with blue light.
(282) We hypothesize that if light has an impact on students
performance and wellbeing, it is by promoting their circadian
entrainment [synchronization] to the solar day, especially in
winter months. Those who are not exposed to enough daylight will
experience a more pronounced delayed circadian phase, which will
result in sleep problems and more severe stress. (284) Figueiro and
Professor of Architecture and Cognitive Sciences Mark Rea postulate
that those who do not get enough shortwavelength light during the
school day will exhibit reduced scholastic performance.(281)
9
III.
The Intersection of School Start Times and Adolescent
Health/Academic Performance
Our study does confirm that on school days adolescents are
obtaining less sleep then they are thought to need, and the factor
with the biggest impact is school start times. If sleep loss is
associated with impaired learning and health, then these data point
to computer use, social activities and especially school start
times as the most obvious intervention points. (28)---Kristen
Knutson, Ph.D., M.A., Assistant Professor of Medicine,
Pulmonary/Critical Care, University of Chicago, Department of
Medicine, Diane Lauderdale, Ph.D., M.A., M.A., Professor of
Epidemiology, University of Chicago. Most high schools begin during
the 7 oclock hour, (12, 21, 22, 23) while melatonin still pressures
adolescents to sleep. (3, 24) Schools begin early for
administrative and financial reasons, rather than because of any
perceived benefits to students. (12, 310) Multi-tiered busing
schedules often save school districts money. (12, 310) High school
students average two hours less sleep on school nights than on
weekends or weekdays during summer. (6, Mindell & Owens,
Clinical Guide to Pediatric Sleep: Diagnosis and Management of
Sleep Problems (Lippincott Williams & Wilkins, 2nd ed. 2010) p.
258.) The starting time of school puts limits on the time available
for sleep. This is a nonnegotiable limit established largely
without concern for sleep. (5) Early high school start time is a
significant, externally imposed constraint on teenagers sleep/wake
schedules; for most adolescents, waking up to go to school is
neither spontaneous nor negotiable. (21) Most teenage students
would sleep longer on school days if not for the typical 7:30 a.m.
or earlier school start-times. (Rauch, What is Normal Sleep for
Children and Adolescents? publish. in, Attention Deficit Disorder:
Practical Coping Mechanisms (Fisher, edit., Informa Healthcare, 2nd
ed. 2007) p. 175, ns. omitted.) Early school start times contribute
substantially to sleep deprivation in teens. (2, 6, 8, [S]chool
sleep lag is worse for earlier starting schools. Additional weekend
sleep does not alleviate this negative effect. (Wahlstrom,
Accommodating the Sleep Patterns of Adolescents Within Current
Educational Structures: An Uncharted Path, publish. in, Adolescent
Sleep Patterns, Biological, Social, and Psychological Influences
(Carskadon, edit., Cambridge Univ. Press 2002) p. 174, ns.
omitted.) Weekend oversleep further contributes to circadian
disruption and decreased daytime alertness levels. (6)21, 22, 23,
26, 27, 28, 29, 31, 32, 33, 38)
Most districts set the earliest starting time for older
adolescents and the latest starting time for younger children.
Ironically, the school starting time moves earlier as childrens
grade advances. Although school starts earlier, children cannot
adjust their bedtime accordingly, and this could result in sleep
deprivation. (Cardinali, Chronoeducation: How the Biological Clock
Influences the Learning Process, publish. in, The Educated Brain:
Essays in Neuroeducation (Battro, Fischer, & Lna, edit.,
Cambridge Univ. Press 2008) p. 121.) [I]ncreasing societal demands
promoted by a10
24/7 culture over the past three decades have contributed to
even earlier school start times for both middle and high school
students. (2) [T]he widespread practice in U.S. school districts
for school buses to run and for the opening bell to ring earlier at
high schools than at junior high schools, and earlier in junior
high schools than primary schools, may run precisely counter to
childrens biological needs. (1) Adolescence is associated with a
circadian phase delay with an increasing preference to sleep at
later hours; despite this, in most U.S. school districts school
days begin progressively earlier as students transition from
elementary to middle school and then from middle school to high
school. (121) Multiple surveys of high school students conducted in
the 1980s and 1990s found that students who start school at 7:30
a.m. or earlier obtain less total sleep on school nights than
students at later starting schools. (21) A study published in 1992
found 12th graders beginning school at 7:40 a.m. reported getting
less school-night sleep, more sleep problems, and sleeping later on
weekends than 12th graders starting school at 8:30 a.m. (34)
(Subjective measures of sleep from children and adolescents are
correlated with objective measures.) (311, 312) In 1994, a study of
3,120 adolescents attending four Rhode Island high schools with
start times ranging from 7:10 a.m.7:30 a.m. found most students
were sleep deficient. 87% of the students reported needing more
sleep than they were getting. (35, 36) Studies published in 2007,
(30) 2009, (28) and 2011 (313) also found that students attending
schools with early start times obtained significantly less sleep
than students at later starting schools. These outcomes are
consistent with the findings of other published studies. (2, 12,
27, 37, 38, 39) An exhaustive search has failed to uncover any
contrary research findings. [E]arly school start times, which our
results indicate were the main predictor of an earlier wake time
among adolescents on school days, conflict with adolescent
circadian biology. The fact that these adolescents spent 2 hours
less time in bed on school days is consistent with one other study
among 60 high school seniors that observed sleep duration reduced
by an average of 2 hours on school days. Another study found that
students attending schools with later start times (8:37 AM versus
7:15 AM) obtained almost an hour more sleep. [O]ur study does
confirm that on school days adolescents are obtaining less sleep
then they are thought to need, and the factor with the biggest
impact is school start times. If sleep loss is associated with
impaired learning and health, then these data point to computer
use, social activities and especially school start times as the
most obvious intervention points. (28)
11
The problem of inadequate sleep affects more segments of our
society than adolescents; however, adolescents appear to be
particularly vulnerable and face difficult challenges for obtaining
sufficient sleep. Even without the pressure of biological changes,
if we combine an early school starting timesay 7:30 a.m., which,
with a modest commute, makes 6:15 a.m. a viable rising timewith our
knowledge that optimal sleep need is 9 hours, we are asking that
16-year-olds go to bed at 9 p.m. Rare is the teenager of the 1990s
who will keep such a schedule. School work, sports practices,
clubs, volunteer work, and paid employment take precedence. When
biological changes are factored in, the ability even to have merely
adequate sleep is lost. (5) Some bus riders may need to awaken
during the 5 oclock hour. (3, 314) The 2011 National Sleep
Foundation poll found 54% of teenagers (13-18 years) awaken between
5 a.m. and 6:30 a.m. on weekdays, with the majority (81%) getting
to bed at 10 p.m. or later. (25) Thus, on school days, 6 in 10
obtain fewer than 8 hours of sleep. (25) Studies of middle school
students have also found early school start times associated with
sleep deficiency and its attendant problems. In addition to the
sleep deficit, school records indicated that students at the
earlier starting school were tardy four times more frequently, and
eighth graders at the earlier starting school obtained
significantly worse average grades than the eighth graders at the
comparison, later starting school. (30) Even pre-adolescent fifth
grade students reported significant sleep deprivation when an
extremely early school start time of 7:10 a.m. was imposed. (315)
Students attending early starting schools are likely to carry
significant chronic sleep debt. (38) Early rise times also
interrupt a critical sleep phase. Getting adequate dream (rapid eye
movement [REM]) sleep is essential to perceptual, cognitive, and
emotional processing. Selective REM sleep deprivation has been
demonstrated to cause symptoms of irritability and moodiness, as
well as problems with memory. The issue of undersleeping in
adolescents takes on added significance when one considers that
waking up too early costs the sleeper mostly REM sleep which
predominates during the last two to three hours of a nights sleep.
(2) In REM sleep, many parts of the brain are as active as at any
time when awake. One study found that REM sleep affects learning of
certain mental skills. People taught a skill and then deprived of
non-REM sleep could recall what they had learned after sleeping,
while people deprived of REM sleep could not. (190) Associate
Professor of Psychology Avi Sadeh, a leading authority in this
field, has concluded that in teens, A loss of one hour of sleep is
equivalent to [the loss of] two years of cognitive maturation and
development. (139, 316)(189)
12
[P]eople who are sleep-deprived are less efficient, thus a cycle
develops in which a student takes longer to complete the same
amount of work, leading to her staying up later, and starting the
vicious cycle all over again. (Mindell & Owens, Clinical Guide
to Pediatric Sleep: Diagnosis and Management of Sleep Problems
(Lippincott Williams & Wilkins, 2nd ed. 2010) p. 258.)
Researchers have also found a general cloud of negative daily
affect that is associated with chronic patterns of inadequate sleep
among adolescents.... (118) Dr. Carskadon is persuaded that these
early school start times are just abusive. (16) Children may feel
adapted to being tired, but performance tests show the opposite.
(317, 318) Although conventional wisdom holds that individuals can
train themselves to adapt to less sleep, laboratory tests belie
this. (319) Chronically sleepdeprived teens often become so used to
the feeling of sleepiness that they dont recognize that they are
settling for less than they are capable of in creativity, academic
performance, and communication both in and out of the classroom.
(Rauch, supra, p. 175.) A 2009 study of Chicago public high schools
found students beginning morning classes at 8 a.m. show marked
deficiencies in performance in first period courses throughout the
term. (320) As in other early starting schools, (2, 30, 41) the
students were more likely to be absent (about 6 more days per year)
in first period relative to other periods. (320, see discussion, n.
570, infra.) [E]arlier start times are associated with significant
sleep deprivation, daytime fatigue, irregular sleep schedules, and
the tendency to fall asleep at school [] This clash between bodily
rhythms and contextual factors can have a wide variety of negative
consequences. Insufficient sleep results in an increased risk for
school absences because of physical illness, falling asleep in
school, oversleeping in the morning, fatigue, and irritability, all
of which are detrimental to academic outcomes[.] (23) Economists
from Columbia University and the University of Michigan calculate
that the earliest school start times are associated with annual
reductions in student performance of roughly 0.1 standard
deviations for disadvantaged students, equivalent to replacing an
average teacher with a teacher at the sixteenth percentile in terms
of effectiveness. (49) A 2005 study published in Pediatrics, the
official Journal of the American Academy of Pediatrics, concluded,
School schedules are forcing [adolescents] to lose sleep and to
perform academically when they are at their worst. (6) A. Academic
Performance Sleep, in essence, is food for the brain. (4)---James
Maas, Ph.D., Retired Professor of Psychology, Stephen H. Weiss
Presidential Fellow, Cornell University. Sleep plays an important
role in learning and memory, (11, 111, 113, 114, 117) with studies
finding an inverse relationship between sleep and academic
performance in children, adolescents, and young adults at every
educational level. (2, 24, 27, 29, 21, 30, 34, 35, 44, 112, 115,
116, 181) Sleep loss is associated with brief mental lapses in
attention during simple tasks that can be13
partially offset by increased effort or motivation. (11, 220)
Tiredness and fatigue, however, tend to diminish motivation,
particularly for tasks perceived as boring or tedious. (220) Sleep
deprivation can sometimes mimic or exacerbate symptoms of ADHD
(attention deficit/hyperactivity disorder), including
distractibility, impulsivity, and difficulty with effortful control
of attention. (220, 11) There is also evidence that sleep
deprivation has marked influences on the ability to perform complex
tasks or tasks that require attention in two or more areas at the
same time. (11, 21, 220) Memory consolidation, long-term recall,
and retrieval, particularly of novel material, are all affected by
sleep restriction. (182) [I]nstalling new memoriesi.e.,
learningclearly benefits from, if not depends upon, intervals of
normal sleep. (2) Not getting enough sleep may result in problems
with attention, memory, decision-making, organization, and
creativity, all of which are clearly important for success in
school. [] [S]tudies actually show that students who get better
grades sleep more, not less. (Mindell & Owens, Clinical Guide
to Pediatric Sleep: Diagnosis and Management of Sleep Problems
(Lippincott Williams & Wilkins, 2nd ed. 2010) p. 258, original
italics.) Scientists have consistently found a constellation of
sleep factorsearlier bedtimes, more total sleep, and later rise
timesassociated with superior academic performance and higher
grades. (2, 29, 30, 34, 181, see also, discussion n. 345, infra.) A
meta-analysis (statistical method combining different study
results) of 61 studies found poor sleep quality, insufficient sleep
and sleepiness significantly associated with worse school
performance among students 8-18 years of age. (340) In 2009, Kyla
Wahlstrom, Director of the Center for Applied Research and
Educational Improvement (CAREI), noted that in schools which have
delayed start times, the academic trend following the change goes
exclusively towards higher grades, (45) an assertion which appears
supported by the evidence. (13, 30, 34, 35, 41, 44, 139, 316, 341,
342) A 2011 study of Israeli middle school students found
significant improvement in mathematics and alphabet attention tasks
when classes were delayed by one hour to 8:30 a.m. (13, 343) The
study strongly recommends that middle schools should consider
delaying the school starting time by at least one hour. Such a
change could enhance students cognitive performance by improving
their attention level, increasing rate of performance, as well as
reducing their mistakes and impulsivity. (13, italics added.)
Similarly, when start times were delayed by one hour, to 9:30 a.m.,
Norwegian 10th graders demonstrated improved performance in
reaction time tests (e.g. psychomotor vigilance tasks), proven as
valid predictors of performance and levels of fatigue[.] (344)
Finley Edwards, Ph.D., compiled test data covering a 10-year period
for middle school students in Wake County, North Carolina. (44)
Edwards found delaying start times by one hour (from 7:30 a.m.)
lead to a 3 percentile point gain in standardized math and reading
test scores for the average middle school student in Wake County,
North Carolina. (44) The improvement was greatest for the bottom
half of the distribution, suggesting that delaying start times may
be particularly important for schools14
attempting to reach minimum competency requirements. (44)
Edwards also found later start times associated with decreased
absences, less time spent watching television and a greater amount
of time spent on homework, indicating that these factors may help
explain why later starting students have higher test scores. (44)
Georgetown University Assistant Professor of Public Policy Peter
Hinrichs has found later start times had no effect on ACT college
entrance exam testing scores in Kansas or Minnesota. (345) As
Hinrichs points out, however, only 59-66% of Minnesota students sat
for the ACT test. (345) (The percentage of Kansas test-takers is
unstated.) Edwards surmises his results differ from Hinrichs
because start times have a greater impact on the bottom half of
students. (44) In 2002, echoing the same point, Wahlstrom noted
Those students who do take these tests [SAT/ACT] typically tend to
be the most academically able, attend classes regularly, and are
likely have study habits that supercede any tiredness they
experience. As a result, it is difficult to compare their scores
with those of their suburban counterparts on nationally normed
tests. (37) Until recently, most researchers did not believe a
cause and effect relationship between later start times and higher
scores had been adequately established. Even so, as Wahlstrom
recognized, there is clearly a statistical relationship between
these two variables that may be explained by other variables (e.g.,
less depression, less struggle to stay awake in class) that change
when the start time of school is changed. (342, emphasis in
original.) One recent study appears to have isolated the effect of
later start times on academic performance. Bearing in mind that
adolescence lasts until around 19.5 years for women and 20.9 years
for men, (7, 103) a four-year study of more than 6,100 first
semester United States Air Force Academy freshman published in the
American Economic Journal: Economic Policy, found a 50 minute delay
in the first class increased grades by 0.15 standard deviations.
(24) The researchers, economists from the United States Air Force
Academy and the University of California, controlled for
potentially confounding factors -- grading structure, class
selection and teachers, for example -- to determine the causal
effect of start times on academic achievement. (24) We find that
when a student is randomly assigned to a first period course
starting prior to 8 a.m., they perform significantly worse in all
their courses taken on that day compared to students who are not
assigned to a first period course. Importantly, we find that this
negative effect diminishes the later the school day begins. [] Our
findings suggest that pushing back the time at which the school day
starts would likely result in significant achievement gains for
adolescents. [] Students with a first period class are
disadvantaged for two reasons. First, they are in class at a time
that their body wants to be asleep, which both makes it difficult
to
15
learn and fatigues the brain. Second, they may be getting less
sleep than their peers who napped during first period. [] Our
findings have important implications for education policy;
administrators aiming to improve student achievement should
consider the potential benefits of delaying school start time. A
later start time of 50 minutes in our sample has the equivalent
benefit as raising teacher quality by roughly one standard
deviation. Hence, later start times may be a cost-effective way to
improve student outcomes for adolescents. (24, italics added.)
Stanford University economist Eric Hanushek calculates that
replacing one average teacher with one above average teacher (one
standard deviation above the mean) for a class of 20 willeach
yearraise students aggregate earnings by more than $400,000. (346)
Economists from Columbia University and the University of Michigan
estimate an increase of $17,500 in individual student earnings in
present value based upon a one hour delay in morning classes, from
roughly 8 a.m. to 9 a.m. (49) Edwards study and the study of Air
Force Academy cadets suggest that changing start time policies
generates these effects for the entire middle or high school. (49)
Professor Maas proposes we reconsider Poor Richards advice. Sleep
deficit is hampering high school achievement. Tiredness should not
be confused with laziness. All teens should have the right to learn
in an optimum environment. Rather than the early to bed... adage,
the new adage should be, Wake up later and your grades will be
greater. (4) B. Depression, Anxiety, and Fatigue Among adolescents,
daily feelings of anxiety, depression, and fatigue are the most
consistent psychological outcomes of obtaining less sleep at night.
(118)---Andrew Fuligini, Ph.D., Professor of Psychiatry &
Biobehavioral Sciences, David Geffen School of Medicine, UCLA,
Christina Hardway, Ph.D., Assistant Professor of Psychology,
University of Michigan. The prevalence of depression increases with
age, especially after the onset of puberty. (380) Excessive
irritability, moodiness, sleep and appetite changes may signal a
vulnerability to depression. (381) [D]epression is not only a
symptom of sleep deprivation but can also be a cause. (381)
Scientists refer to this as a bidirectional relationship (Dobson
& Dozois, Risk Factors in Depression (Academic Press 2008) p.
109), or bidirectional causal pathway. (23) Adolescents who present
with depression display high rates of sleep disturbance and those
who present with complaints of poor sleep display high rates of
depression. This may create a perpetual cycle, where lack of sleep
leads to feelings of fatigue and apathy at school, impaired
16
academic and social functioning, reduced levels of motivation,
and impaired ability to regulate mood and emotional responses.
(119) Depressed children often report disturbed sleep despite
normal architecture measured by electroencephalography. (134)
Adolescents who are anxious, depressed, or feel less healthy may in
fact, need more sleep than those with better psychological
functioning. The challenges of getting through an ordinary day may
require increased energy for these adolescents. (134) Depressed
adolescents frequently have difficulty falling asleep, are unable
to get up or refuse to go to school, sleep until late in the day,
complain of extreme daytime fatigue, and, over time, shift to
increasingly more delayed sleep-wake schedules. (220) Reports of
depression have been shown to decline in schools which have delayed
start times. (3, 37, 41, 47) Depression is linked to suicidal
ideation in teens. (380, 382, 383) C. Suicidal Ideation and
Completed Suicide The majority of children who attempt or
contemplate suicide are likely to suffer from depression. (380,
382, 383) Sleep loss or disturbances may signal an increased risk
of future suicidal action in adolescents. (120, 121, 122, 123, 124)
A 2011 study published in the Journal of Psychiatric Research found
that children who had trouble sleeping at 12 to 14 years of age
were more than twice as likely to have suicidal thoughts at ages 15
to 17. (400, 401) The association between short sleep duration and
suicidality has been hypothesized to be due, in part, to the
negative effects of insufficient sleep on judgment, concentration,
and impulse control. (121) Sleep problems and sleep deficiency have
long been associated with suicidal ideation in teens. (52, 53, 400)
Suicide is the third leading cause of death among adolescents, in
recent years accounting for 10% or more of all teen fatalities.
(402, 403) Recent data put the suicide rate in the general
population at 2.7%. (404) Poor academic performance is among the
risk factors for teen suicidality. (382, 405) As previously noted,
sleep deficiency is closely associated with poor academic
performance. (2, 27, 29, 30, 34, 35) D. Psychomotor
Performance/Automobile Accidents Sleep deprivation, whether from
disorder or lifestyle, whether acute or chronic, poses significant
cognitive risks in the performance of many ordinary tasks such as
driving and operating machinery. (420)---Jeffrey S. Durmer, M.D.,
Ph.D., Assistant Professor, Department of Neurology, Emory
University School of Medicine, David F. Dinges, Ph.D., Professor of
Psychology in Psychiatry, Associate Director, Center for Sleep and
Circadian Neurobiology, University of Pennsylvania School of
Medicine.
17
There is increasing evidence correlating early start times with
higher crash rates among adolescents. (31, 46, 421, 422) Both motor
and mental acuity suffer when we are sleep deprived, which can lead
to dangerous human errors and accidents. Studies done on test
subjects with occupations associated with sleep
deprivationincluding pilots, truck drivers, and medical
residentstypically show a greater risk for fatigue-related mistakes
and crashes. Accidents related to lost lives and billions of
dollars in costs. (Abaci, Take Charge of Your Chronic Pain: The
Latest Research, Cutting-Edge Tools (Globe Pequot Press 2010) p.
241, n. omitted.) In 1999, school districts in Lexington, Kentucky
delayed start times for high school students county-wide by one
hour to 8:30 a.m. (31) Average crash rates for teen drivers in the
study county in the 2 years after the change in school start time
dropped 16.5%, compared with the 2 years prior to the change,
whereas teen crash rates for the rest of the state increased 7.8%
over the same time period. (31) The researchers concluded that
allowing adolescents to sleep more on school nights by delaying the
start of school not only results in them sleeping more, but also
may have a measurable positive effect on their driving safety. (31)
In reviewing the study, John Cline, Assistant Clinical Professor of
Psychiatry at the Yale School of Medicine, commented, Given the
danger posed to young people from car accidents this is a strong
reason in itself to change school start times. (423) A 2011 study
published in the Journal of Clinical Sleep Medicine found that in
2008, the teen crash rate was about 41% higher in Virginia Beach,
Virginia, where high school classes began at 7:207:25 a.m., than in
adjacent Chesapeake, Virginia, where classes started an hour later
at 8:408:45 a.m. (421) Although a cause and effect relationship has
not been established, the Virginia study associates early start
times with increased teenage car crash rates. (46, 422) We were
concerned that Virginia Beach teens might be sleep restricted due
to their early rise times and that this could eventuate in an
increased crash rate, said lead author Robert Vorona, M.D.,
Associate Professor of Internal Medicine at Eastern Virginia
Medical School in Norfolk, Virginia. (421) Similar results were
found for 2007, when the weekday crash rate for Virginia Beach
teens (71.2) was 28 percent higher than for Chesapeake teens
(55.6). (46) In a secondary analysis that evaluated only the
traditional school months of September 2007 through June 2008, the
weekday crash rate for teen drivers was 25 percent higher in
Virginia Beach (80.0) than in Chesapeake (64.0). (46) The morning
peak in crash rates occurred one hour earlier in Virginia Beach
than in Chesapeake. (46) The congestion data for Virginia Beach and
Chesapeake did not explain the different crash rates. (46, 422) Dr.
Vorona contends delaying high school start times may promote driver
alertness by reducing the severity of chronic sleep restriction, a
common problem during adolescence. (421) We believe that high
schools should take a close look at having later start times to
align with circadian rhythms in teens and to allow for longer
sleep
18
times. Too many teens in this country obtain insufficient sleep.
A burgeoning literature suggests that this may lead to problematic
consequences including mood disorders, academic difficulties and
behavioral issues. (421) Harvard Professor of Medicine Stuart Quan
concurs: They are additional data suggesting that high school start
times should be delayed to increase the amount of sleep that
teenagers get during the school week and, hence, reduce the amount
of sleep deprivation they incur. (343) Teenagers, especially older
teenage boys, are at the highest risk for falling asleep at the
wheel. The most common drowsy driving accident involves a single
vehicle with a single driver who drives off the road. These
accidents happen most often late at night and in the middle of the
afternoon. So dont be fooled that just because it is bright
daylight, your teen wont fall asleep at the wheel. In addition, all
teens who are not getting enough sleep are at risk, especially when
a beer or two, marijuana, and relative driving inexperience
compound lack of sleep. (Mindell & Owens, Clinical Guide to
Pediatric Sleep: Diagnosis and Management of Sleep Problems
(Lippincott Williams & Wilkins, 2nd ed. 2010) p. 258.)
Consistent with previous studies, (2) a five year study by the Ohio
Department of Transportation released in August of 2011 showed that
7 a.m. is the most dangerous time for teens driving to school.
(424) Given that the sleep-inducing hormone, melatonin, pressures
adolescents to sleep until approximately 8 a.m., (3, 24) this
outcome should not be surprising. Nationally, sleepiness is the
leading cause of motor vehicle crashes among drivers 16 to 29 years
of age. (21, 46, 425) Psychomotor impairment due to sleep
deprivation, as seen on tests like driving performance, can
resemble that seen with blood alcohol levels between .05 and .10
percent. (426, 427, 428, Abaci, supra.) Motor vehicle crashes are
the leading cause of death for U.S. teens, accounting for more than
one in three deaths in this age group. (403, 177) E. Athletic
Performance Sleep is a universal recovery strategy that is
essential to both physiological adaptation and to the consolidation
of skill development[.] (440) Sleep deprivation and sleep
disturbance can impair mental and physical function, immune
response and other restorative processes important for athletes.
(440) Athletes should aim for 10 hours of sleep per night.
Adolescent athletes may need more sleep. (440) Just as insufficient
sleep is associated with diminished athletic/psychomotor
performance, (126, 420, 426, 427, 428) so extra sleep is correlated
with improved athletic/psychomotor performance. (125) The benefits
of extra sleep for athletes have been established repeatedly. (441,
442, 443, 444, 445) Increased sleep is associated with faster
reaction
19
times, (141, 446) improved peripheral vision, (447) and peak
athletic performance. (448) Sleepiness, by contrast, can increase
the risk of sports injuries in teens. (449) Dr. Phil Eichling, a
sleep medicine specialist, notes that peripheral vision can be
affected by loss of sleep resulting in slow eye movement. (447)
Decreased peripheral vision is a huge competitive disadvantage for
athletes. (447) Sleep duration may be an important consideration
for an athletes daily training regimen, according to Dr. Cheri Mah
of the Stanford Sleep Disorders Clinic and Research Laboratory.
Furthermore, sleep extension also may contribute to minimizing the
effects of accumulated sleep deprivation and thus could be a
beneficial strategy for optimal performance. (450) Dr. Mahs 2010
study of college athletes found most entered training with sleep
deficits. The athletes were encouraged to press for extra sleep, up
to 10 hours nightly. After several weeks of consistent additional
sleep, athletic performance began to improve. (450, 451) While most
athletes and coaching staff may believe that sleep is an important
contributing factor in sports, many do not realize that optimal or
peak performance can only occur when an athletes sleep and sleep
habits are optimal. (448, 452) F. Excessive Weight Gain A study
published in the September 2010 issue of the journal Sleep found
that teenagers who slept less than eight hours per weeknight ate
more fatty foods and snacks than adolescents who slept eight hours
or more. (470) For each one-hour increase in sleep duration, the
odds of consuming a high amount of calories from snacks decreased
by an average of 21 percent. (129, 470) A significantly greater
proportion of teens who slept less than eight hours per weeknight
consumed food in the early morning between 5 a.m. and 7 a.m. (129,
470) According to Harvards Dr. Susan Redline, Altered timing of
eating in shorter sleepers also may be a metabolic stress that
contributes to metabolic dysfunction. (129, 470) Obviously, being
awake for longer hours means more opportunities to eat. Weight gain
may be promoted by eating at a time when circadian rhythm dictates
sleep. (471) A 2010 CDC study published in the Journal of the
American Medical Association reports that the rate of obesity in
U.S. adolescents between the ages of 12 and 19 years was 18.1
percent in 2007-2008. (472) The authors noted that the prevalence
of high body mass index in childhood has remained steady for 10
years and has not declined despite coordinated prevention efforts.
(472) Overweight children and adolescents tend to have reduced REM
sleep. (128) Although a recent study suggests otherwise, (473) Dr.
Redline and other researchers
20
surmise sleep loss may be the missing link (129) in
understanding why diet and exercise obesity interventions fail.
(127, 130, 474, 475) G. Risk-Taking & Delinquent Behavior
Risk-taking is a complex phenomenon, and adolescents seem to be a
particularly vulnerable population. (131)--- Erin M. OBrien, Ph.D.,
Instructor in Psychiatry and Human Behavior, The Warren Alpert
Medical School, Brown University, Jodi Mindell, Ph.D., Professor of
Psychology, Director, Graduate Program, St. Josephs University,
Associate Director, Sleep Center, Childrens Hospital of
Philadelphia. In ruling the Eighth Amendment (barring cruel and
unusual punishment) prohibits imposing the death penalty for
juvenile offenders, the United States Supreme Court noted
differences between juvenile and adult offenders. Writing for the
Courts majority, Justice Kennedy observed, First, as any parent
knows and as the scientific and sociological studies respondent and
his amici cite tend to confirm, [a] lack of maturity and an
underdeveloped sense of responsibility are found in youth more
often than in adults and are more understandable among the young.
These qualities often result in impetuous and ill-considered
actions and decisions. It has been noted that adolescents are
overrepresented statistically in virtually every category of
reckless behavior. In recognition of the comparative immaturity and
irresponsibility of juveniles, almost every State prohibits those
under 18 years of age from voting, serving on juries, or marrying
without parental consent. [] The second area of difference is that
juveniles are more vulnerable or susceptible to negative influences
and outside pressures, including peer pressure. (`[Y]outh is more
than a chronological fact. It is a time and condition of life when
a person may be most susceptible to influence and to psychological
damage). (490) The adolescent qualities referenced by Justice
Kennedypsychological vulnerability, impulsivity, immature judgment,
susceptibility to negative influence and peer pressuretend to be
exacerbated by restricted sleep. (52, 53, 121, 131, 132, 134)
Adolescents inability to control emotional responses when sleep
deprived could influence aggression, sexual behavior, the use of
alcohol and drugs, and risky driving. (21) Teenagers who are sleep
deprived are often more impulsive and more likely to engage in
risk-taking behaviors, such as drinking, driving fast, and engaging
in other dangerous activities. (Mindell & Owens, Clinical Guide
to Pediatric Sleep: Diagnosis and Management of Sleep Problems
(Lippincott Williams & Wilkins, 2nd ed. 2010) p. 258.) Despite
the robust health typical of adolescents, death rates soar at this
age largely because of misfortunes associated with elevated
risk-taking behaviors, including use of alcohol and other drugs
that may further increase the incidence of risky21
behaviors. Adolescence may be a vulnerable period not only
because of the high prevalence of risk-taking, but also because of
the potential lasting consequences of perturbations to the brain as
it is sculpted during this time. For instance, brain regions
undergoing particularly marked remodeling during adolescence (e.g.,
PFC, amygdala, nucleus accumbens) are among those that are most
sensitive to alcohol and other drugs of abuse. (Coch, Fischer,
& Dawson, Human Behavior, Learning, and the Developing Brain:
Typical Development (Informa Healthcare 2010) p. 383, citations
omitted.) One unintended consequence of the earlier school schedule
is the amount of unstructured time some teens are faced with after
school in the afternoons. This selfcare time lends itself to
greater risk taking, and has been correlated with increased
substance use and depressed mood. Indeed, juvenile crimes are four
times more likely to occur in the hours after school than at other
times during the day or night. (2, 310) A study published last year
in the Journal of Youth and Adolescence found that teenagers
sleeping seven or fewer hours per night had a significantly higher
rate of property crimes such as vandalism, shoplifting, and
breaking and entering than their peers who had 8-10 hours of sleep.
(133) Teenagers sleeping five or fewer hours per night had a
significantly higher rate of violent crimes such as being involved
in a physical fight or threatening someone with a weapon than those
teenagers who had slept 8-10 hours. (133) The researchers note, Our
analysis provides preliminary evidence that sleepdeprived
adolescents participate in a greater volume of both violent and
property crime.... Further, our results indicate that every little
bit of sleep may make a difference. That is, sleeping 1 (hour) less
(i.e., 7 hours) than the recommended range increased the likelihood
of property delinquency, and this risk increased for each hour of
sleep missed. (133) In a 2005 study of 388 Philadelphia high school
students, 67% of participants indicated that they thought they
obtained too little sleep. (131) Researchers found students
reporting more sleep problems were also more likely to report that
they were experiencing behavior problems and substance use. (131)
Students who obtained the least amount of sleep on school nights
reported greater alcohol usage than those students who obtained the
most sleep on school nights, and those students with the biggest
difference between their school-night and weekend-night bedtimes
reported higher levels of risk-taking behavior and lower academic
performance. (131) Overall, the results of this study support the
expectation that inadequate sleep and increased sleep problems have
negative effects on adolescents daytime functioning, including
poorer academic performance, increased daytime sleepiness, negative
moods, behavior problems, and increased risk-taking. (131)
22
A 2011 CDC study of 12,154 high school students also found an
association between diminished sleep and increased likelihood of
health-risk behaviors, including use of cigarettes, alcohol, or
marijuana, sexual activity, and serious consideration of attempting
suicide. (53) These outcomes appear to be universal. A survey of
6,632 students from 349 secondary schools across Italy found an
association between increased complaints of daytime sleepiness and
poor academic achievement, greater use of caffeine, alcohol, and
tobacco, sleep problems, evening phase preference, anxiety, and
depressive mood. (Gianotti & Cortesi, Sleep Patterns and
Daytime Function in Adolescents: An Epidemiological Survey of an
Italian High School Student Sample, publish. in, Adolescent Sleep
Patterns: Biological, Social, and Psychological Influences,
(Carskadon, edit., Cambridge Univ. Press 2002) pp. 132-147.) Lela
McKnight-Eily, Ph.D., lead author of the recent CDC study, recently
commented, consideration of delayed school start times may hold
promise as one effective step in a comprehensive approach to
address this problem. (52) Stimulant Use Young people are
increasingly using caffeine to compensate for chronic inadequate
sleep. (106, 491) Ironically, falling asleep in school is
associated with high caffeine consumption. (105) Caffeine, a
methylxanthine and adenosine receptor antagonist, can be considered
the most commonly consumed psychoactive substance worldwide. (105)
Of the 5,448 US caffeine overdoses reported in 2007, 46% occurred
in those younger than 19 years. (212) Currently, the U.S. does not
regulate the amount of caffeine in energy drinks. (492) Energy
drinks are classified as dietary supplements rather than sodas and
are not limited by the same caffeine restrictions that are applied
to soft drinks. (492) The FDA limits regular soft drinks to a
maximum of 71 milligrams of caffeine per 12 ounce can, however,
these limits do not apply to most energy drinks. (492) According to
self-report surveys, energy drinks are consumed by 30% to 50% of
adolescents and young adults. (492) Reports indicate that some high
school students drink as many as five cans of energy drinks a day
to combat sleep loss. (29) Frequently containing high and
unregulated amounts of caffeine, these drinks have been reported in
association with serious adverse effects, especially in children,
adolescents, and young adults with seizures, diabetes, cardiac
abnormalities, or mood and behavioral disorders or those who take
certain medications. (492) Clusters of Sleep/Drug Use Behavior
Researchers from Harvard and the University of California mapped
the social networks of 8,349 adolescents in order to study how
sleep behavior spreads, how drug use behavior spreads, and how a
friends sleep behavior influences ones own drug use. (132) Their
study found clusters of poor sleep behavior and drug use that
extend up to four degrees of separation (to ones friends friends
friends friends) in the social
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network. [I]f a friend sleeps