Chapter 10.2

Jet lag

a period of discomfort and inefficiency while your internal clock is out of phase with your new surroundings.

Circadian rhythm

a rhythm of activity and inactivity lasting about a day.

Activation-synthesis theory of dreams

according to it, dreams occur because the cortex takes the haphazard activity that occurs during REM sleep plus whatever stimuli strike the sense organs and does its best to make sense of this activity.

Rapid eye movement (REM) sleep or paradoxical sleep

during this stage of sleep, the sleeper's eyes move rapidly back and forth under the closed lids.

Melatonin

is important for both circadian rhythms and many species' annual rhythms of reproduction, hibernation, and so forth

Orexin

is important for maintaining long periods of wakefulness.

Neurocognitive theory

is that dreaming is simply a kind of thinking, similar to daydreaming or mind wandering, that occurs under these conditions, reduced sensory stimulation, loss of voluntary control of thinking, and enough activity in other brain areas.

Insomnia

means lack of sleep, not enough sleep for the person to feel rested the next day.

Sleep apnea

means no breathing, failing to breathe for a minute or more and then wake up gasping for breath.

Electroencephalograph (EEG)

measures and amplifies tiny electrical changes on the scalp that reflect patterns.

REM behavior disorder

people with this condition fail to inhibit their muscular activity during REM, and as a result, they sometimes walk around flailing their arms.

Narcolepsy

people with this condition lose the brain cells that produce orexin, and therefore return to a pattern resembling infants. They experience sudden attacks of sleepiness during the day.

Polysomnography

produced when combining an EEG measure with a simultaneous measure of eye movements.

Periodic limb movement disorder

prolonged "creepy-crawly" sensations in their legs, accompanied by repetitive leg movements strong enough to awaken the person, especially during the first half of the night.

Later shift

that is, someone working from 8 a.m. to 4 p.m. shifts to the 4 p.m. to midnight time (like traveling west) instead of midnight to 8 a.m. (like traveling east).

Suprachiasmatic nucleus

the circadian rhythm of sleep and wakefulness is generated within the brain by a tiny structure.

Manifest content

the content that appears on the surface.

Latent content

the hidden ideas that the dream experience represents symbolically.

Default network

the system active during mind wandering and daydreaming.

Sleep spindles

waves of activity at about 12 to 14 per second.