front 1 Circadian rhythm | back 1 Circadian rhythms are the physical, mental, and behavioral changes an organism experiences over a 24-hour cycle |
front 2 Dreams | back 2 a series of thoughts, images, and sensations occurring in a person's mind during sleep. |
front 3 Electroencephalograph (EEG) | back 3 electroencephalogram (EEG) is a test that measures electrical activity in the brain using small, metal discs |
front 4 Hypersomnia | back 4 a condition in which you feel extreme daytime sleepiness despite getting sleep that should be adequate (or more than adequate) |
front 5 Insomnia | back 5 a common sleep disorder that can make it hard to fall asleep or stay asleep |
front 6 Melatonin | back 6 a hormone that your brain produces in response to darkness |
front 7 Napping | back 7 sleep lightly or briefly, especially during the day. |
front 8 Narcolepsy | back 8 a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles |
front 9 Night Terrors | back 9 feelings of great fear experienced on suddenly waking in the night. |
front 10 Nightmares | back 10 a disturbing dream associated with negative feelings, such as anxiety or fear that awakens you |
front 11 Parasomnia | back 11 occur in a state that lies between sleep and wakefulness |
front 12 Restless Legs Syndrome | back 12 a condition that causes a very strong urge to move the legs |
front 13 Sleep | back 13 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. |
front 14 Sleep apnea | back 14 a potentially serious sleep disorder in which breathing repeatedly stops and starts |
front 15 Sleep deprivation | back 15 occurs when an individual fails to get the amount of sleep that they need. |
front 16 Sleep paralysis | back 16 a temporary loss of muscle control just after falling asleep or before waking up |
front 17 Sleep study | back 17 a test used to diagnose sleep disorders |
front 18 Snoring | back 18 the hoarse or harsh sound that occurs when air flows past relaxed tissues in your throat, causing the tissues to vibrate as you breathe |
front 19 Stage 1 (Non-REM) sleep | back 19 heartbeat, eye movements, brain waves, and breathing activity begin to taper down. |
front 20 Stage 2 (Non-REM) sleep | back 20 Stage 2 is still light sleep, but deeper than stage 1 |
front 21 Stage 3 (Non-REM) sleep | back 21 This is considered the deepest stage of sleep and is characterized by signals with lower frequencies and higher amplitudes, known as delta waves |
front 22 Stage 4 (REM Sleep | back 22 your voluntary muscles become immobilized. |
front 23 Somnambulism | back 23 most often occurs during deep, non-REM sleep (called N3 sleep) early in the night |
front 24 Wakefulness | back 24 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 |