front 1 Circadian rhythm | back 1 physical, mental, and behavioral changes that follow 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 a machine used for electroencephalography. |
front 4 Hypersomnia | back 4 medical conditions in which you repeatedly feel excessively tired during the day (called excessive daytime sleepiness) or sleep longer than usual at night |
front 5 Insomnia | back 5 a common sleep disorder |
front 6 Melatonin | back 6 a hormone that your brain produces in response to darkness |
front 7 Napping | back 7 A midday nap can enhance alertness, mood, memory, and reduce stress |
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 a sleep disorder in which a person quickly awakens from sleep in a terrified state |
front 10 Nightmares | back 10 a frightening or unpleasant dream. |
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 an uncontrollable urge to move the legs, usually because of an uncomfortable sensation |
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 inadequate or insufficient sleep sustained over a period of time |
front 16 Sleep paralysis | back 16 a temporary inability to move or speak that occurs directly after falling asleep or waking up |
front 17 Sleep study | back 17 painless tests that measure how well you sleep and how your body responds to sleep problems |
front 18 Snoring | back 18 caused by the rattling and vibration of tissues. View Source near the airway in the back of the throat |
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 a continued slowing of heartbeat, breathing, muscle activity, and eye movements. |
front 21 Stage 3 (Non-REM) sleep | back 21 N3 or deep sleep, |
front 22 Stage 4 (REM Sleep) | back 22 your voluntary muscles become immobilized. |
front 23 Somnambulism | back 23 sleepwalking. |
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. |