front 1 Circadian rhythm | back 1 the body's natural 24-hour cycle that regulates various physiological and behavioral processes, including sleep-wake patterns, body temperature, hormone release, and digestion |
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 medical test that measures the electrical activity of the brain using electrodes placed on the scalp |
front 4 Hypersomnia | back 4 excessive daytime sleepiness |
front 5 Insomnia | back 5 a common sleep disorder characterized by difficulty falling asleep, staying asleep, or experiencing poor-quality sleep, even when there's adequate opportunity and circumstance for sleep |
front 6 Melatonin | back 6 a hormone secreted by the pineal gland which inhibits melanin formation and is thought to be concerned with regulating the reproductive cycle. |
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 regulate sleep-wake cycles |
front 9 Night Terrors | back 9 episodes of intense fear and panic that occur during sleep |
front 10 Nightmares | back 10 a frightening or unpleasant dream. |
front 11 Parasomnia | back 11 any of a group of sleep disorders characterized by the regular occurrence of abnormal movements, vocalizations, or experiences, such as sleepwalking, talking in one's sleep, or night terrors. |
front 12 Restless Legs Syndrome | back 12
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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 sleep disorder characterized by pauses in breathing during sleep |
front 15 Sleep deprivation | back 15 a state where an individual does not get enough sleep or experiences poor-quality sleep |
front 16 Sleep paralysis | back 16 a temporary condition that occurs when a person is falling asleep or waking up |
front 17 Sleep study | back 17 a medical test that monitors and records various physiological parameters during sleep to diagnose and manage sleep disorders |
front 18 Snoring | back 18 the action or fact of making a snorting or grunting sound while asleep. |
front 19 Stage 1 (Non-REM) sleep | back 19 the lightest stage of sleep, a transitional period between wakefulness and deeper sleep, characterized by slowed brainwaves, breathing, and heart rate, and where you can be easily awakened. |
front 20 Stage 2 (Non-REM) sleep | back 20 a deeper stage of light sleep than stage 1, characterized by a slowed heart rate, breathing, and body temperature, along with the appearance of sleep spindles and K-complexes in brainwave activity |
front 21 Stage 3 (Non-REM) sleep | back 21 characterized by slow, high-amplitude brain waves (delta waves), making it the deepest stage of sleep and the most difficult to wake from |
front 22 Stage 4 (REM Sleep) | back 22 the deepest stage of sleep characterized by slow brain waves, reduced heart rate and breathing, and relaxed muscles, where the body repairs tissues, builds bone and muscle, and strengthens the immune system |
front 23 Somnambulism | back 23 sleepwalking. |
front 24 Wakefulness | back 24 the state of being awake, conscious, and alert, characterized by the ability to respond to external stimuli and engage in coherent cognitive and behavioral functions, the opposite of sleep |