Chapter 7: Consciousness Part II – Sleep. Sleep “The equalizer of presidents and peasants” Used to be full of mysteries – now we are starting to solve.

Chapter 7: Consciousness

Part II – Sleep

Sleep

• “The equalizer of presidents and peasants”

• Used to be full of mysteries – now we are starting to solve those mysteries

• We can measure brain waves and muscle movements and combined with watching, we are learning many things

Rhythms

• Life has rhythms like everything else on earth• So does sleep• Controlled by biological clocks• In a 24 hours cycle we experience variations in

alertness, body temperature, and growth hormone secretion

• Sleep has a rhythm and cycle too!– 90 minutes for humans

Circadian Rhythm• It is the biological clock that occurs on the 24

hour cycle• Temperature rises in the morning, peaks during

the day, and dips in the early afternoon, and drops before bed time

• If you are awake in the middle of the night you may be more susceptible to depressed thoughts

• All nighter? Most tired at 4:00 am, although we may get a second wind at a normal “rising” time

• Jet lag! We have disrupted the cycle

The Role of Light• Light is what tweaks the circadian clock• Light-sensitive proteins trigger signals to the brains

suprachiasmatic nucleus– 20,000 cells that control the circadian clock

• Pineal gland adjusts how much melatonin is being produced– Decrease melatonin production in the morning, increase

at night (light and dark)• Longer we are awake the more adenosine

accumulates– Adenosine inhibits certain neurons, making us sleepy– Amount of adenosine decreases when we are asleep– Caffeine blocks adenosine activity

Sleep Stages

• Sleep overtakes, cortex stop communicating, consciousness fades

• Every 90 minutes we pass through 5 sleep stages

• We can measure the stages with electrodes, and EEG, and other devices to measure heart rate, respiration and genital arousal

Sleep Stage…Step-by-Step

• “Pre-Sleep”: Awake, but eyes are closed; slow alpha waves; fall asleep (enter into stage 1)

• Step/Stage 1: Sleep; slowed breathing; irregular brain waves; hallucinations (sensory experiences without sensory stimulus)– EX: body may suddenly jerk or you may feel like

you are falling– Hypnagogic sensations– May later be remembered as memories

Sleep Stage…Step-by-Step

• Step/Stage 2: Sleep (still); more relaxation; lasts about 20 minutes; can be awakened easily; sleep talking; sleep spindles– Bursts of rapid, rhythmatic brain-wave activity

• Step/Stage 3: Sleep (yep…still); transitional stage; slower delta waves; 30 minutes long; hard to wake up

• Step/Stage 4: Deep sleep (still sleep – just deep); slow delta waves; 30 minutes; hard to wake up– Oddly, it is at the end of stage 4 that children wet the bed

or sleepwalking begins

While We Are Sleeping…..• Brain can still process certain stimuli• We move in our beds and don’t fall out (we

hope)• Auditory cortex is still responding to sound

(especially our names)• An hour into sleeping, we do not stay in stage 4,

we go back through stage 3 and 2• We spend half of the night in stage 2– REM sleep

REM Sleep• REM – Rapid Eye Movement• 10 minutes at a time• Brain waves are rapid and saw-toothed• Heart rate rises; breathing more rapid and irregular; eyes

dart around• Genitals become aroused during REM (except nightmares)• Motor cortex is active in REM, but brainstem blocks the

messages, so your muscles stay relaxed• Internally aroused, externally calm• REM announces the beginning of a dream• Not that we are watching our dream, but that nervous

system is overactive

Sleep Through the Night• Cycle repeats about every 90 minutes• As the night goes on, stage 4 gets shorter and

then disappears and REM gets longer• We spend 20-25% of the night in REM

0 1 2 3 4 5 6 7

4

3

2

1Sleepstages

Awake

Hours of sleep

REM

People Vary – Sleep Varies

• Most of us would sleep 9 hours if we set no clocks, routines or other hindrances

• There is no rule as to how many hours EVERY person MUST have

• Varies from person to person• Age changes needs• Genetics? Culture?

Why?

• Why do we sleep?• 1/3 of our lives (25 years)• If you want to know why – stay awake for 3

days and you will find out! Or watch someone who has been up that long

Sleep Deprivation

• Teenagers typically need 8-9 hours a night, but they average less than 7

• When you don’t have enough sleep you function below your peak

• Depressed immune system, impaired concentration, vulnerability to accidents, diminished productivity, fatigue (duh), irritability,…to quote the book…it makes you stupid

Are You Sleep Deprived?

• http://www.webmd.com/sleep-disorders/excessive-sleepiness-10/breus-sleep-deprived

• Quiz: http://www.health24.com/tools/Quizzes/1891-1892,114.asp

My Teacher Lied!!! (Kinda)• You can catch up on sleep• We have a “sleep debt”• Our body knows what we are behind and when we

catch it up, it will go back to a normal requirement• Volunteers were paid to stay in bed 14 hours a day.• For the first few days most slept 12 hours• Once they paid off their sleep debt, they went back

to 7.5-9 hours a night• Millions of us are living in debt and living less than

optimal lives

And for the “kinda” part….

• Many people sleep late on Saturday, hoping to compensate for sleep lost during the week. While sleeping late helps catch up on your sleep debt, it alters your sleep schedule. You sleep late one or two days and then wake up early again on Monday. Your body must adjust to these changes. During this adjustment, your quality of sleep is poor. It is much better to have a consistent daily sleep schedule that gives you 7 to 9 hours each night.

And…Despite What My Hubby Says

• Naps can be a great way to catch up on lost sleep. After taking naps, people function better and do certain cognitive tasks quicker. Napping can also help you train yourself to fall asleep quicker. However, napping longer than an hour or after 3 p.m. may make it more difficult for you to fall asleep at night.

Sleep Disorders Insomnia

persistent problems in falling or staying asleep 10-15% if adults (17-20% of teens) Sleeping pills and alcohol actually make it worse

Narcolepsy uncontrollable sleep attacks Last 5 minutes 1/2000 people Must live with extra caution

Sleep Apnea temporary cessation of breathing and momentary re-

awakenings Overweight men (most common) “Loud snoring”

Night Terrors and Nightmares

Night Terrors Mostly kids high arousal-- appearance of being terrified Double heart and respiration rate Don’t usually wake up or remember anything They are NOT nightmares Occur within 2 or 3 hours of falling asleep, usually

during Stage 4

End Day 2

• Homework!• Get permission to watch someone sleep (please ask

and do not freak them out – it would be kinda creepy for you to watch them without them knowing)

• Watch them for 90 minutes (please do not multi-task, but only do things that do not draw away your attention/consciousness – auto pilot baby!)

• Write down your observations (this should keep you awake and alert)

• When done, summarize in 1-2 paragraphs and turn in with your notes