1. Unit V: States of Consciousness Module 23-Sleep Patterns & Sleep Theories
AP Psychology

2. Circadian Rhythm Circadian rhythm and age
Circadian rhythm-our “biological clock,” regular body rhythms
24 hour cycle
Temperature changes
Body temp rises in the morning, peaks during the day, dips in the early afternoon, & drops in the evening
Circadian rhythm and age
Typically, teens/young adults are at their peak as the day progress
Older adults tend to see their performance decline as the day progresses
This shift usually occurs around 20 (slightly sooner for women)

3. Brain Waves
Alpha Waves-relatively slow brain waves of a relaxed, awake state
Beta Waves-brain waves during a heightened states of alertness, logic and critical reasoning
can translate into stress, anxiety and restlessness
Delta Waves-usually associated with the deep stage 3 of NREM sleep
Theta Waves-present during deep meditation and light sleep
REM dream state

4. Sleep Stages Two distinct types of sleep:
REM Sleep-rapid eye movement sleep; also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active
Vivid dreams are typical during this stage of sleep
NREM Sleep-non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep.

5. Sleep Stages We typically go through 4 sleep stages every 90 minutes:
NREM1
slow eye movement.
sometimes referred to as relaxed wakefulness
Alpha waves begin to disappear
People aroused from this stage often believe that they have been fully awake
NREM2
no eye movement occurs
dreaming is very rare
The sleeper is quite easily awakened

6. Sleep Stages We typically go through 4 sleep stages every 90 minutes:
NREM3
deep sleep
dreaming is more common in this stage than in other stages of NREM sleep (though not as common as in REM sleep)
REM
rapid eye movement, increased heart beat, irregular breathing
vivid dreams commonly occur
Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active

7. Sleep Stages
Although the stages are numbered NREM 1, 2, 3, REM; they don’t occur in that order:
Typically, NREM 1 occurs first
NREM 2
NREM 3
REM
The cycle repeats every 90 minutes or so
As the night goes on, NREM 3 sleep becomes shorter & disappears
REM & NREM 2 periods get longer

8. Sleep Stages

9. What Affects Our Sleep Patterns?
Suprachiasmatic nucleus (SCN)-a pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, the SCN causes the pineal gland to adjust melatonin production, thus modifying our feelings of sleepiness.
Melatonin-hormone that induces sleep

10. HW-Using your textbook and/or other sources, identify and explain the 5 reasons psychologists believe that sleep might have evolved in humans.