Conciousness

Stage 1

Produces theta and fast beta waves; lasts 5 minutes; person can be easily woken.

Stage 2

Characterized by sleep spindles (bursts of electrical activity); lasts about 20 minutes.

Stage 3

Involves some delta waves, lasts approximately 30 minutes, and is a non-REM stage.

Stage 4

Mostly delta waves, lasts 30 minutes, is non-REM, and is the deepest sleep with night terrors and sleepwalking.

REM Sleep

Also known as paradoxical sleep; involves sleep paralysis, dreams, and is a lighter sleep compared to stage 4.

Hypnagogic State

The transitional state between wakefulness and sleep.

Sleep Paralysis

Occurs during REM to prevent acting out dreams.

Paradoxical Sleep

A state during REM where the body is paralyzed, but the mind remains active.

REM Rebound

Lengthened REM duration following a night of insufficient deep sleep.

Sleep Apnea

A condition in which breathing stops multiple times during the night, affecting 10% of people who snore.

Narcolepsy

A disorder characterized by uncontrollable sleep attacks, causing direct entry into REM sleep.

Fatal Insomnia

An inability to enter any sleep stage.

Sleeping Beauty Syndrome

A condition where an individual has difficulty waking up for a majority of the day.

REM Sleep Behavior Disorder

A condition where normal paralysis during REM sleep is absent.

Night Terrors

Episodes of intense fear and anxiety that manifest during sleep.

Insomnia

A sleep disorder characterized by an inconsistent sleep cycle or difficulty in sleeping.

Adenosine

A chemical in the brain that promotes feelings of tiredness and sleepiness, suppressed by caffeine.

Somnambulism

More commonly known as sleepwalking; typically occurs in stage 3.

Biological Rhythm

Cycles in biological systems such as yearly, seasonal, or menstrual cycles.

Circadian Rhythm

The daily physiological cycles that are considered the most important.

Information Processing Theory

A theory suggesting that dreams help consolidate memories and sort daily events.

Activation Synthesis Theory

A theory positing that dreams result from the brain's attempt to make sense of random electrical impulses.

Physiological Function Theory

Suggests that regular brain stimulation during REM sleep aids in developing and preserving neural pathways.

Neural Activation Theory

Proposes that REM sleep triggers neural activities that evoke memories, which are then transformed into dreams.

Cognitive Development Theory

A theory that dream content reflects the dreamer's cognitive development and knowledge.

Coma

A state in which the individual does not experience sleep cycles.

Hypnosis

A trance-like state between sleep and wakefulness characterized by heightened suggestibility.

Depressants

Substances that relax the nervous system.

Stimulants

Substances that energize the mind and body.

Hallucinogens

Substances that induce altered states of consciousness.