Sleep and Learning November 17, 2011

Sleep and LearningNovember 17, 2011

November 17, 2011

“It has been documented in a handful of major studies that children, from elementary school through high school, get about an hour less sleep each night than they did 30 years ago.”

Po Bronstein, Nurture Shock

“A loss of one hour of sleep is equivalent to [the loss of] two years of cognitive maturation and development,”

Avi Sadeh, Tel Aviv University

We see in many adolescents that this forbidden zone is in the evening hours. So they actually feel great at night and, for many of them, that makes it harder for them to even consider trying to go to bed earlier.

Mary Carskadon, Brown University

[D]uring sleep, the brain shifts what it learned that day to more efficient storage regions of the brain. Each stage of sleep plays a unique role in capturing memories. For example, studying a foreign language requires learning vocabulary, auditory memory of new sounds, and motor skills to correctly enunciate new words. The vocabulary is synthesized by the hippocampus early in the night during “slow-wave sleep,” a deep slumber without dreams. The motor skills of enunciation are processed during Stage 2 Non-REM sleep, and the auditory memories are encoded across all stages. Memories that are emotionally laden get processed during REM sleep. The more you learned during the day, the more you need to sleep that night.

Dr. Matthew Walker, UC Berkeley

Negative stimuli get processed by the amygdala; positive or neutral memories get processed by the hippocampus.

Sleep deprivation hits the hippocampus harder than the amygdala.

The result is that sleep-deprived people fail to recall pleasant memories yet recall gloomy memories just fine.

“Inconsistent bedtimes are, for all practical purposes, homemade jet lag—the desynchronization of the two systems that regulate sleep, the circadian rhythm and the homeostatic pressure system. Staying up three hours later on weekends is equivalent to flying across three time zones every weekend.”

Ashley Merryman, How to Get Kids to Sleep More, 2007

A different mechanism causes children to be inattentive in class. Sleep loss debilitates our body’s ability to extract glucose from the bloodstream. Without this stream of basic energy, one part of the brain suffers more than the rest: the prefrontal cortex, which is responsible for what’s called “executive function.”

Dysfunction of the prefrontal cortex may result in a negative impact on such functions as creative thinking and goal-oriented behavior, resulting in a wide range of disruptive and even violent behavior. (Dahl, 1996)

A tired brain perseverates—it gets stuck on a wrong answer and can’t come up with a more creative solution, repeatedly returning to the same answer it already knows is erroneous.

In some ways, these busy overachievers are those who concern the experts the most. According to University of Minnesota’s Dr. Kyla Wahlstrom, a motivated student can sacrifice sleep to maintain high GPAs, but she may pay for that success with higher levels of depression and stress.

In Edina, Minnesota, an affluent suburb of Minneapolis, where the high school start time was changed from 7:25 a.m. to 8:30. The results were startling. In the year preceding the time change, math and verbal SAT scores for the top 10 percent of Edina’s students averaged 1288. A year later, the top 10 percent averaged 1500, an increase that couldn’t be attributed to any other variable.

Results from Other Studies on School Start Times

• In a study comparing sleep patterns of students in a school with a late start time (9:30 a.m.) and a school with an early start time (7:20 a.m.), students in the school with the late start averaged 7.5 hours of sleep per night vs. 6.9 hours in the early start school. (Kowalski and Allen, 1995, as referenced in Mitru)

• A study comparing demographically similar schools showed that students in schools with later start times slept one hour more than students in schools with earlier start times. (Frederickson & Wrobel, 1997, as referenced in Mitru)

• A study comparing Minnesota high school students in schools with late start times vs. schools with early start time found that in the later schools:

- the average score measuring depression found significantly lower depression;

- the average number of student sick days was significantly fewer;

- there was greater alertness exhibited during class time, exams, and activities;

- there were fewer tardies resulting from oversleeping. (Wahlstrom, et al., 1998)

Trends in Adolescent Sleep Behavior & Recent Research

• The onset of puberty brings with it a sleep-phase delay in their circadian rhythms, which causes a tendency to go to bed later and wake later. (Dahl, Carskadon)

• Adolescent sleep requirements do not decline as they mature. In fact, there is evidence that more sleep is required as they mature. (Carskadon)

• Adolescents generally sleep less as they mature, due to societal and school schedule pressures. (Carskadon)

• While adolescents require between 8.5 and 9.25 hours of sleep per night, over 25% report getting less than 6.5 hours of sleep on school nights. (Dahl)

• 60% of children under 18 acknowledged tiredness and sleepiness during the day, and 15% admitted to falling asleep in school. (Dahl)

• Parental control over bedtime may diminish when children are 12-13. (Carskadon, 1999)

The researchers [at Stanford] asked the players to maintain a typical nighttime schedule, sleeping six to nine hours, between two to four weeks before attempting to sleep for 10 hours each night over a six week period.  During the course of the study, researchers found that the players ran faster timed sprints; dropping their times from 16.2 seconds at the beginning of the experiment to 15.5 seconds at the end.  Their shooting accuracy also increased by 9% and fatigue levels dropped. The athletes even reported better performance during competitive basketball games.

http://www.youtube.com/watch?v=Ovtrq0g56lE

http://www.youtube.com/watch?v=WmRGNunPj3c