Circadian rhythm
the physical, mental, and behavioral changes an organism experiences over a 24-hour cycle.
dreams
a series of thoughts, images, and sensations occurring in a person's mind during sleep
Electroencephalograph (EEG)
a recording of brain activity.
Hypersomnia
a condition in which you feel extreme daytime sleepiness despite getting sleep that should be adequate (or more than adequate)
Insomnia
having trouble falling asleep, staying asleep, or getting good quality sleep.
Melatonin
a hormone that your brain produces in response to darkness
Napping
sleeping for a short time during the day
Narcolepsy
a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles
Night Terrors
a sleep disorder in which a person quickly awakens from sleep in a terrified state
Nightmares
a disturbing dream associated with negative feelings, such as anxiety or fear that awakens you
Parasomnia
Parasomnias occur in a state that lies between sleep and wakefulness
Restless Legs Syndrome
a condition that causes a very strong urge to move the legs
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 potentially serious sleep disorder in which breathing repeatedly stops and starts
Sleep deprivation
occurs when an individual fails to get the amount of sleep that they need
Sleep paralysis
a temporary inability to move or speak that occurs directly after falling asleep or waking up
Sleep study
a test used to diagnose sleep disorders
Snoring
the action or fact of making a snorting or grunting sound while asleep
Stage 1 (Non-REM) sleep
heartbeat, eye movements, brain waves, and breathing activity begin to taper down
Stage 2 (Non-REM) sleep
You are in light sleep. Your heart rate slows and your body temperature drops.
Stage 3 (Non-REM) sleep
deep sleep, and it is harder to wake someone up if they are in this phase.
Stage 4 (REM Sleep)
your voluntary muscles become immobilized. Your brain also uses this time to cement information into memory, making it an important stage for learning
Somnambulism
sleep walking
Wakefulness
a condition of being alert, rather than sleepy.