1. Sleep Patterns and Theories
MODULE 23

2. Circadian Rhythm 24hr cycle of day & night
Body temp increases through the day, dips slightly in the mid afternoon (siesta) and falls in the evening
Thinking & memory are most accurate when people are at their peak in circadian arousal.
Morning/Night person? With age we tend to shift from being owls to larks

3. Sleep Sleep is a state of consciousness.
We are less aware of our surroundings.
Parts of the cortex stop communicating but are still active.

4. Waking Up and Falling Asleep
Morning light tweaks circadian clock  activates light-sensitive retinal proteins
Signals brains suprachiasmatic nucleus (SCN) in the hypothalamus
Pineal gland
Stop producing melatonin in the AM
Start producing melatonin in the PM

5. Sleep Cycle Use an EEG machine to measure stages of sleep.
4 distinct stages
When you are in the onset of sleep (getting ready to fall asleep) you experience alpha waves.
ONE CYCLE LASTS 90 MINUTES

7. Non-REM Stage 1 (NREM-1) Kind of awake and kind of asleep.
Only lasts a few minutes, and you usually only experience it once a night.
May experience hallucinations – sensory experiences without stimulation
feeling of falling or floating
jerking body movements
Feeling pinned

8. Non-REM Stage 2 (NREM-2) Lasts about 20 min
Begin to show sleep spindles…short bursts of rapid brain waves.
Clearly asleep but can be easily woken up
Sleep talking (nonsensical/garbled) can occur in this stage or later

9. Non-REM Stage (NREM-3)
Slow wave sleep.
You produce Delta waves.
Hard to awaken… you will be very groggy.
Vital for restoring body’s growth hormones and good overall health.
Lasts about 30 min.
Young children may experience bedwetting/sleepwalking
At the end of NREM-3 you ascend back up through NREM-2 to reach REM

10. REM Sleep Rapid Eye Movement
Often called paradoxical sleep because the body is internally aroused & externally calm
Brain is very active.
Dreams usually occur in REM
Emotional, usually story like and richly hallucinatory
Body is essentially paralyzed – motor cortex is active but signals are blocked by the brainstem
Lasts about 10 minutes
Heart rate rises, rapid irregular breathing, eyes dart around, genitals become aroused

11. REM Sleep
During the night, REM and NREM-2 sleep increases and NREM-3 becomes shorter.
Sleep cycle repeats itself about every 90 min.
By morning, 20-25% of night’s sleep has been spent dreaming (about 100 min = 600 hours/year = 15,000 dreams = 100,000 dreams/lifetime)
37% of people report few/no dreams but under experimental conditions  woken up during REM they will recall some details of a dream

12. Stages in a Typical Night’s Sleep1 2 3 4 5 6 7
Sleep
stages
Awake
Hours of sleep
REM

13. How much sleep do we need?
Range in humans – 4-10 hours with average of 7.5 hours. Why does it vary?
Varies with age & from person to person
Newborns 2/3 of the day (16 hrs)
Adults 1/3 of the day (8 hrs)
Sleep patterns are culturally influenced
US: typically 7-8 hrs… much less than our past
Modern light bulb, shift work, social diversions/technology
Time zones/travel, daylight savings

14. How much sleep do we need?
Stanley Coren study (1996)
Found most people will sleep 9+ hrs uninterrupted.
Don’t get groggy
Awake refreshed, with better moods, perform more efficient & accurate work than those with less sleep.

15. Sleep Theories Sleep protects us Sleep lets us recuperate
Darkness increases danger – species dependent on vision
We were safer in a cave/shelter/house
Sleep lets us recuperate
Restore and repair brain tissue
Sleep is when fading memories are restored
Consolidates memory
People recall performance task training better after sleep … even a short nap

16. Sleep Theories 4. Sleep feeds creative thinking
Dreams are sources of inspiration
Enhances problem solving, learning and spotting connections
5. Sleep supports growth
Pituitary gland releases a growth hormone  necessary for muscle development
Dramatically improves athletic performance
Babies sleep 16 hours vs. elderly sleep 6 hours