Psychology Module 8

Sleep

A naturally occurring altered state of consciousness marked by a diminished sense of awareness and responsiveness to the external environment.

Hypnogogic state

The transitional period between wakefulness and sleep, characterised by vivid and dreamlike sensory experiences as an individual drifts off to sleep.

Hypnic jerk

An involuntary muscle contraction or sudden twitch that occurs as a person is falling asleep, often accompanied by a sensation of falling.

Hypnogram

A graphic representation of the transition between stages of sleep over time.

Delayed sleep-wake phase disorder

A circadian phase disorder that delays sleep patterns.

Advanced sleep-wake phase disorder

A circadian phase disorder that brings sleep patterns forward, often seen in the elderly.

Sleep debt

The accumulated amount of sleep loss from insufficient sleep.

Evolutionary theory of sleep

The theory that sleep serves to increase an animal's or human's chance of survival in its environment.

Restoration theory of sleep

A theory stating that sleep allows us to recharge our bodies, and recover from the physical and psychological work during the day; it also allows our body's growth processes to occur.

Adenosine

A neurotransmitter produced when our cells use energy and that accumulates when we are awake.

Norepinephrine

A neurotransmitter involved in regulating arousal that helps keep us alert during the day.

Partial sleep deprivation

Having some sleep in a 24-hour period but not getting enough to meet your needs; may occur for just one night or for several nights and can have serious consequences.

Total sleep deprivation

Going without sleep for an entire 24-hour period; may occur for just one night or for several nights.

Chronic sleep deprivation

Not getting enough sleep over an extended period of time; long-term sleep deprivation.

REM rebound

The significantly larger amount of time spent in REM sleep than usual that follows a period of being deprived of REM sleep.