Circadian rhythm
Circadian rhythms are the physical, mental, and behavioral changes an organism experiences over a 24-hour cycle
Dreams
a series of thoughts, images, and sensations occurring in a person's mind during sleep.
Electroencephalograph (EEG)
electroencephalogram (EEG) is a test that measures electrical activity in the brain using small, metal discs
Hypersomnia
a condition in which you feel extreme daytime sleepiness despite getting sleep that should be adequate (or more than adequate)
Insomnia
a common sleep disorder that can make it hard to fall asleep or stay asleep
Melatonin
a hormone that your brain produces in response to darkness
Napping
sleep lightly or briefly, especially during the day.
Narcolepsy
a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles
Night Terrors
feelings of great fear experienced on suddenly waking in the night.
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 that causes a very strong urge to move the legs
Sleep
a condition of body and mind that typically recurs for several hours every night, in which the eyes are closed, the postural muscles relaxed, the activity of the brain altered, and consciousness of the surroundings practically suspended.
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 loss of muscle control just after falling asleep or before waking up
Sleep study
a test used to 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
Stage 2 is still light sleep, but deeper than stage 1
Stage 3 (Non-REM) sleep
This is considered the deepest stage of sleep and is characterized by signals with lower frequencies and higher amplitudes, known as delta waves
Stage 4 (REM Sleep
your voluntary muscles become immobilized.
Somnambulism
most often occurs during deep, non-REM sleep (called N3 sleep) early in the night
Wakefulness
a daily recurring brain state and state of consciousness in which an individual is conscious and engages in coherent cognitive and behavioral responses to the external world