Chapter 14 – Sleep, Dreaming, and Circadian Rhythms

Polysomnography

Measurement of EEG EOG and EMG to study sleep stages.

Alpha waves

8–12 Hz low amplitude waves associated with relaxed wakefulness.

Theta waves

4–7 Hz waves seen in light sleep stage 1.

Delta waves

High amplitude waves under 4 Hz found in deep slow-wave sleep.

Sleep spindles

12–14 Hz bursts of EEG activity that occur during stage 2 sleep.

K-complex

A large negative spike followed by a positive wave that occurs during stage 2 sleep.

REM sleep

Sleep stage with beta-like EEG waves rapid eye movements and muscle atonia.

Activation–Synthesis theory

Dreams result from the brain’s attempt to interpret random neural signals from the brainstem.

Freud’s theory of dreaming

Dreams are disguised wish fulfillment of unconscious desires.

Recuperation theory

Sleep restores energy and repairs damage from wakefulness.

Adaptation theory

Sleep evolved to conserve energy and protect during inactivity.

Sleep deprivation effects

Causes fatigue poor focus mood swings and microsleeps.

Suprachiasmatic nucleus

Brain area in hypothalamus that serves as the body’s circadian clock.

Zeitgebers

External cues like light and temperature that synchronize circadian rhythms.

Hypnotic drugs

Medications like benzodiazepines that promote sleep but reduce deep and REM sleep.