front 1 Circadian rhythm | back 1 are the physical, mental, and behavioral changes an organism experiences over a 24-hour cycle. Light and dark have the biggest influence on circadian rhythms, but food intake, stress, physical activity, social environment, and temperature also affect them. |
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 is a test that measures electrical activity in the brain using small, metal discs (electrodes) attached to the scalp. Brain cells communicate via electrical impulses and are active all the time, even during asleep. This activity shows up as wavy lines on an EEG recording. |
front 4 Hypersomnia | back 4 is a condition in which you feel extreme daytime sleepiness despite getting sleep that should be adequate (or more than adequate). If you have hypersomnia, you fall asleep several times during the day. |
front 5 Insomnia | back 5 is a common sleep disorder. With insomnia, you may have trouble falling asleep, staying asleep, or getting good quality sleep. This happens even if you have the time and the right environment to sleep well. Insomnia can get in the way of your daily activities and may make you feel sleepy during the day. |
front 6 Melatonin | back 6 is a hormone that your brain produces in response to darkness. It helps with the timing of your circadian rhythms (24-hour internal clock) and with sleep. Being exposed to light at night can block melatonin production. |
front 7 Napping | back 7 is a short period of sleep, typically taken during daytime hours as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours. |
front 8 Narcolepsy | back 8 is a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles. |
front 9 Night Terrors | back 9 Episodes of screaming, intense fear, and flailing while still asleep, often paired with sleepwalking. |
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. A person with parasomnias may seem to be alert, walking or talking or eating or doing other such activities but without awareness because the brain is only partially awake. |
front 12 Restless Legs Syndrome | back 12 A condition characterized by a nearly irresistible urge to move the legs, typically in the evenings. |
front 13 Sleep | back 13 is a state of reduced mental and physical activity in which consciousness is altered and certain sensory activity is inhibited. |
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 feeling of being conscious but unable to move. |
front 17 Sleep study | back 17 a test that records the activity of the body during sleep. There are five main types of sleep studies that use different methods to test for different sleep characteristics and 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 when a person first falls asleep. This stage normally lasts just one to seven minutes. |
front 20 Stage 2 (Non-REM) sleep | back 20 the body enters a more subdued state including a drop in temperature, relaxed muscles, and slowed breathing and heart rate. At the same time, brain waves show a new pattern and eye movement stops. |
front 21 Stage 3 (Non-REM) sleep | back 21 deep sleep |
front 22 Stage 4 (REM Sleep) | back 22 he predominant EEG activity consists of low frequency (1–4 Hz), high-amplitude fluctuations called delta waves, |
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. |