1. Sleep and Dreams

2. Circadian Rhythms
Biological rhythms that occur approximately every 24 hours
Ex. Sleep-wake cycle
Regulated by suprachiasmatic nucleus (SCN) located in the hypothalamus

3. Hypothalamus Sleep control center in the brain
Monitors changes in light or dark in the environment
Changes levels of hormones in the body

4. Melatonin
Hormone released by pineal gland that helps regulate daily biological rhythms
Linked to the sleep-wake cycle
Increases during the night and decreases with exposure to morning light

5. Reasons for Sleep
Preservation: keep us protected from the dangers of the night
Restoration: recuperate from the wear and tear of the day
Restore and rebuild memories: strengthens and stabilizes neural memory traces
Feeds creative thinking: dreams inspire
Supports growth: pituitary gland releases growth hormone

6. Electroencephalograph (EEG)
Machine that amplifies and records waves of electrical activity that sweep across the brain’s surface
Electrodes placed on the scalp measure the waves

7. Beta Waves: Small fast waves associated with alertness and awakeness
Alpha Waves: Large, slow waves associated with relaxation and falling asleep
Delta Waves: long, slow waves that indicate the deepest stage of sleep

8. Typical Night’s Sleep (90 min. cycle)
With Each 90 min. cycle, stage 4 sleep decreases and the duration of REM sleep increases

9. Two types of Sleep: NREM & REM

10. Stage 1 Sleep (NREM-1) Breathing is slowed
Brain waves become irregular
It is easy to wake the person, who will insist they are not asleep
Rarely lasts longer than 5 minutes
Hypnagogic sensation: false sensory experiences

11. Stage 2 Sleep (NREM-2) Brain wave cycle slows--shift to Theta waves
First time through stage 2 last about 20 minutes
Deeper sleep
Sleep spindles-short burst of brain activity
K Complex

12. Stage 3 & 4 Sleep (NREM-3 & 4)
Delta waves first appear—very large and slow
Transition to stage 4—deepest stage of sleep
Almost purely delta waves

13. REM Sleep
Rapid eye movement (REM Sleep) as eyes move quickly back and forth
Vivid dreaming occurs in REM sleep
Considered “paradoxical sleep”

14. Paradoxical Sleep
During REM sleep brain wave patterns are similar to when a person is awake
Pulse and breathing quickens
Physiology is close to that of being awake (motor cortex is active) but the brainstem blocks all muscle movement

15. Sleep Changes through Life

16. Sleep Deprivation

17. Sleep Deprivation Effects
Decreases efficiency of immune system functioning
Safety and accident issues
Contributes to hypertension, impaired concentration, irritability, etc.

18. Sleep Deprivation

19. Sleep Disorders and Sleep Problems

20. Insomnia Recurring problems falling asleep or staying asleep
Sleeping pills tend to inhibit or suppress REM sleep; worsen the problem
Alcohol suppresses REM sleep; also worsens the problem
Studies show most people overestimate how long it took them to get to sleep

21. Narcolepsy
Sleep disorder characterized by uncontrollable sleep attacks
Person may lapse directly into REM sleep
Nervous system getting aroused tends to trigger the sleep attack

22. Night Terrors
Sleep disorder characterized by high arousal and appearance of being terrified
Unlike nightmares
Happens during stage 4 sleep; mostly children
The children seldom remember the event.

23. Sleep Apnea
Sleep disorder characterized by temporary cessations of breathing during sleep and consequent momentary reawakenings.
Tend to be loud snorers
Continuous Positive Airway Pressure machine

24. Somnambulism Formal name for sleepwalking
Starts in the deep stages of N-REM sleep
Person can walk or talk and is able to see
Rarely has any memory of the event

25. Theories of Why Do We Dream?

27. Freud’s Wish-fulfillment
Dreams provide a “psychic safety valve”—expressing otherwise unacceptable feelings
Contain Manifest content
Remembered story line of a dream
Contain Latent content
the underlying meaning of a dream

28. Information-Processing Theory
Dreams serve an important memory- related function by sorting and sifting through the day’s experiences
Research suggests REM sleep helps memory storage.

29. Physiological Function Theory
Neural activity during REM sleep provides periodic stimulation of the brain.

30. Activation-Synthesis Theory
Dreams are the mind’s attempt to make sense of random neural firings in the brain as one sleeps.

31. Cognitive Development Theory
Dreams part of the maturation process
Dreams reflect our knowledge
Reflection of normal cognitive development