Sleep and Dreams

Psychology

Stages of Sleep

• Stages 1 to 4: From light to deep sleep• Stage 1: brain waves become small and

irregular with varying frequencies. You can be easily awakened during this stage and may not even realize that you had been sleeping.

Stage 2

• Stage 2 Sleep begins about two minutes after Stage 1 and is characterized by bursts of brain wave activity that are represented by spindle-shaped waves called sleep spindles. You spend more than ½ your sleep in Stage 2

• This is a deeper stage of sleep, but you can still be readily awakened.

Stages 3 and 4

• Both stages are called delta sleep or slow-wave sleep (SWS), these stages are characterized by the appearance of large, slow brain waves called delta waves. This is the period of deep sleep, when it is difficult to arouse you.

Distinction b/w Stage 3 and 4

• Based on the proportion of delta waves.

• Stage 3, delta waves constitute 50% or fewer of the brain wave patterns

• Heart rate and breathing slow down.

• Stage 4, delta waves constitute more than 50%

• Deepest point of in the sleep cycle occurs.

• If you were roused from this stage of deep sleep, you would be groggy and confused

REM sleep

• After 30 to 45 minutes in stage 4, you quickly return to stages 3 and 2. Then you enter a special stage in which your eyes move rapidly under their closed eyelids

• Rapid Eye Movement (REM) sleep• In REM sleep the EEG resembles that of an

awake, alert person, and your physiological arousal is similar to when you are awake.

• REM is a sign of dreaming

REM sleep

• Your muscles are nearly paralyzed. Sudden twitchy spasms appear, especially in your face and hands, but your brain activity suppresses other movements.

• Sleep paralysis occurs• Paradoxical sleep= internally, your body is

aroused; externally, you’re the picture of calm and hard to awaken.

Non-REM sleep

• The interim periods, w/o rapid eye movements

• Sleepwalking and sleep talking occur during the deepest stage of NREM sleep

Sleep Debt

• Most people require between 7-9 hours of sleep to feel fully refreshed and to function at their best.

• Some people are sleep-deprived and do not realize it.

• Children spend more time in REM sleep, but as they mature the proportion of REM sleep declines, while periods of NREM sleep and wakefulness increase.

Dreams A story like episode of unfolding mental imagery

during sleep. No one really knows why we dream.

Brain structures

• Brain stem• Amygdala• Hippocampus

Dreams

• 1. Freud’s theory of Dreams• Dreams serve as sources of wish fulfillment.• Manifest vs. Latent ContentStory line symbolic meaning

of dreams

Theories/hypothesis

• 2. Activation-synthesis hypothesis= dreams represent an attempt by the cerebral cortex to make sense of the random discharges of electrical activity that occur during REM sleep.

• Cerebral cortex creates a story line based on the individual’s store of knowledge and memories to explain these random signals and the emotions/sensory experiences they generate.

Crick-Mitchison view

• 3. Theory: we dream to forget, unravel those neural nets…dreams’ function is to take out the mental trash. “get rid of our stress”

Memory Consolidation Theory

• 4. Dreams help us remember and process events of the day.

• Dreams help us solve some of our daily problems.

The End

• So cute….