1. Sleep

2. Learning objectives
What are daily rhythms and how are they maintained?
What is sleep?
How do we characterize different phases of sleep?
What is REM and NREM sleep?
How does sleep change with age?
What are the health effects of sleep (or lack of sleep)
What is the difference between dyssomnias and parasomnias?

3. Rhythms Circannual rhythms hibernation, migration Fertility cycles
monthly in humans
Circadian Rhythm
Daily

4. Circadian Rhythm Maintained by suprachiasmic nuclei (SCN)
controls body temp, alertness
inactive at night, allowing sleep
Signals for the release of melatonin by pineal gland
hormone that increases relaxation and sleepiness
Resets due to light
Mismatch between internal and external cues induces insomnia or sleepiness — jet lag

5. What is sleep?
A state of unconsciousness or partial consciousness from which a person can be roused by stimulation (i.e. not a coma)
Strongly influenced by circadian rhythms

6. Structure of sleep Non-rapid eye movement sleep (NREM)
Rapid eye movement sleep (REM)

7. NREM sleep Stage 1 relaxed, half-awake state “nope, I wasn’t asleep”
no movement — stimulates sleep
admit to being asleep
Stages 3 & 4
deep sleep
Blood pressure drops, heart and respiration slow
Most deep sleep in beginning of night

8. REM sleep Breathing and heart rate increase
brain activity increases, dreaming
REM sleep paralysis
brain seems awake
no muscle tone
REM rebound effect
more frequent REM after inadequate sleep
We ‘file’ ideas and thoughts in long-term memory
People lacking REM sleep can’t learn complex tasks

9. Structure of sleep REM increases throughout night
“Deep sleep” most likely during first cycles

10. Irregular temperature cycling
Sleep and age
More deep sleep
Irregular temperature cycling
Less melatonin

11. Health effects of sleep
Metabolism
less sleep —> higher obesity rates
alters glucose metabolism
hormone imbalance
ghrelin = increases appetite
leptin = decreases appetite
less REM (which burns calories)
more cortisol (encourages food binges)

12. Health effects of sleep
Safety
Sleep deprivation —> drowsiness
loss of 1 hour sleep at daylight savings time coincides with 20% increase in auto accidents the next day
Heart Disease
Immune function

13. Health effects of sleep
Cancer
Shift workers more likely to get breast and prostate cancer
changes in hormones? immune system suppression? decreased melatonin?
Mental health
sleep complaints common in schizophrenic, bipolar, and depressive patients

14. Possible reasons why we need sleep
Wound healing, growth, and restoration
Immune system function decreases with lack of sleep
More growth hormone at night
Waste clearance in brain
Brain development
Filing memories into long-term memory
Especially during REM sleep

15. How much sleep do we need?
8-9 hours for most people
varies by individual
Sleep deprivation
less sleep than needed to feel ‘vibrant’
Sleep debt
sleeping in on weekends usually NOT enough
Signs of insufficient sleep:
Daytime drowsiness
falling asleep ‘as soon as you head hits pillow’

16. How to get a good night’s sleep
Maintain a regular schedule
Sleep in conducive environment (cool, quiet, comfortable)
Avoid caffeine, nicotine, and alcohol
Get exercise (but not too close to bedtime, > 3hrs)
Manage stress
Short naps only
pull the plug (computers and lights keep you from falling asleep)

17. Sleep disorders Dyssomnias Parasomnias
Difficulty falling asleep, staying asleep, or excessive sleepiness
Insomnia
Sleep apnea
narcolepsy
brain’s inability to control sleep-wake cycles
Parasomnias
physiological functioning or behavior during sleep
Usually occur between wake and NREM sleep
sleepwalking
sleep-related eating disorder

18. Sleep aids Prescription Lunesta and Ambien Can be addictive
side effects include cognitive distortion
sleep driving
sleep related binge eating
should not be taken form more than 2 weeks
Over-the-counter
antihistamines
promote drowsiness but the body develops tolerance