Circadian rhythm
the body's natural 24-hour cycle that regulates various physiological and behavioral processes, including sleep-wake patterns, body temperature, hormone release, and digestion
Dreams
a series of thoughts, images, and sensations occurring in a person's mind during sleep.
Electroencephalograph (EEG)
a medical test that measures the electrical activity of the brain using electrodes placed on the scalp
Hypersomnia
excessive daytime sleepiness
Insomnia
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
Melatonin
a hormone secreted by the pineal gland which inhibits melanin formation and is thought to be concerned with regulating the reproductive cycle.
Napping
sleep lightly or briefly, especially during the day.
Narcolepsy
a chronic neurological disorder that affects the brain's ability to regulate sleep-wake cycles
Night Terrors
episodes of intense fear and panic that occur during sleep
Nightmares
a frightening or unpleasant dream.
Parasomnia
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.
Restless Legs Syndrome
- a disorder characterized by the occurrence of uncomfortable sensations in the legs and the urge to move them in order to relieve the sensations, typically occurring in the evening or at night and often interfering with sleep.
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 sleep disorder characterized by pauses in breathing during sleep
Sleep deprivation
a state where an individual does not get enough sleep or experiences poor-quality sleep
Sleep paralysis
a temporary condition that occurs when a person is falling asleep or waking up
Sleep study
a medical test that monitors and records various physiological parameters during sleep to diagnose and manage sleep disorders
Snoring
the action or fact of making a snorting or grunting sound while asleep.
Stage 1 (Non-REM) sleep
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.
Stage 2 (Non-REM) sleep
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
Stage 3 (Non-REM) sleep
characterized by slow, high-amplitude brain waves (delta waves), making it the deepest stage of sleep and the most difficult to wake from
Stage 4 (REM Sleep)
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
Somnambulism
sleepwalking.
Wakefulness
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