1.5 states of consciousness and sleep

Consciousness

Our subjective awareness of ourselves and our environment

Cognitive neuroscience

The interdisciplinary study of the brain activity linked with mental tasks like thinking, knowing, remembering, and communicating

Sleep

A periodic, natural loss of consciousness – as distinct from unconsciousness resulting from a coma, general anesthesia, or hibernation

Circadian rhythm

Our biological clock; regular body cycles (for example, of temperature and wakefulness) that occur on a 24-hour cycle

Jet lag

A disruption in a person's circadian rhythm, the body's internal clock, which occurs when traveling across multiple time zones

EEG patterns

Patterns of brain activity at different states of consciousness, including different stages of sleep

REM sleep (Rapid eye movement sleep)

A recurring sleep stage during which vivid dreams commonly occur. Also known as paradoxical sleep, because the muscles are relaxed (except for minor twitches) but other body systems are active

Alpha waves

The relatively slow brain waves of a relaxed, awake state

NREM sleep

Non-rapid eye movement sleep; encompasses all sleep stages except for REM sleep

Hallucinations

False sensory experiences, such as seeing something in the absence of an external visual stimulus

Hypnagogic sensations

Bizarre experiences, such as jerking or a feeling of falling or floating weightlessly, while transitioning to sleep

Delta waves

The large, slow brain waves associated with deep sleep

Suprachiasmatic nucleus (SCN)

A pair of cell clusters in the hypothalamus that controls circadian rhythm. In response to light, it adjusts melatonin production, thus modifying our feelings of sleepiness.

Insomnia

Recurring problems in falling or staying asleep

Narcolepsy

A sleep disorder characterized by uncontrollable sleep attacks. The affected person may lapse directly into REM sleep, often at inopportune times.

Sleep apnea

A sleep disorder characterized by temporary cessations of breathing during sleep and repeated momentary awakenings

REM sleep behavior disorder

A sleep disorder in which normal REM paralysis does not occur; instead, twitching, talking, or even kicking or punching may occur, often acting out one’s dream

Somnambulism

Sleepwalking; a sleep disorder where a person performs complex motor activities while in a state of partial sleep and partial wakefulness

REM rebound

The tendency for REM sleep in increase following REM sleep deprivation

Dream

A sequence of images, emotions, and thoughts passing through a sleeping person’s mind

Activation synthesis theory

The idea that dreams are our brain’s attempt to make sense of spontaneous, random neural activity during REM sleep

Consolidation theory

The idea that dreams are the result of our brain processing and organizing memories and new learnings from the day’s events