Circadian rhythm

the physical, mental, and behavioral changes an organism experiences over a 24-hour cycle

Dreams

Dreams are stories and images that our minds create while we sleep.

Electroencephalograph (EEG)

a recording of brain activity.

Hypersomnia

excessive sleepiness

Insomnia

a common sleep disorder. With insomnia, you may have trouble falling asleep, staying asleep, or getting good quality sleep.

Melatonin

a hormone in your body that plays a role in sleep.

Napping

a short period of sleep, typically taken during daytime hours as an adjunct to the usual nocturnal sleep period.

Narcolepsy

a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles.

Night Terrors

a sleep disorder in which a person quickly awakens from sleep in a terrified state.

Nightmares

a disturbing dream associated with negative feelings, such as anxiety or fear that awakens you.

Parasomnia

occur in a state that lies between sleep and wakefulness.

Restless Legs Syndrome

A condition characterized by a nearly irresistible urge to move the legs, typically in the evenings.

Sleep

Sleep is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited.

Sleep apnea

a potentially serious sleep disorder in which breathing repeatedly stops and starts.

Sleep deprivation

occurs when an individual fails to get the amount of sleep that they need.

Sleep paralysis

a temporary inability to move or speak that occurs directly after falling asleep or waking up.

Sleep study

diagnose sleep disorders.

Snoring

the hoarse or harsh sound that occurs when air flows past relaxed tissues in your throat, causing the tissues to vibrate as you breathe.

Stage 1 (Non-REM) sleep

heartbeat, eye movements, brain waves, and breathing activity begin to taper down

Stage 2 (Non-REM) sleep

is still light sleep, but deeper than stage 1.

Stage 3 (Non-REM) sleep

Deep sleep

Stage 4 (REM Sleep)

an even deeper sleep where the brain waves further slow and sleepers are very difficult to wake.

Somnambulism

Sleep walking

Wakefulness

a condition of being alert, rather than sleepy.