circadian rhythm
physical, mental, and behavioral changes that follow a 24-hour cycle
Dreams
a succession of images, ideas, emotions, and sensations that usually occur involuntarily in the mind during certain stages of sleep
Electroencephalograph (EEG)
a medical test used to measure the electrical activity of the brain
Hypersomnia
medical conditions in which you repeatedly feel excessively tired during the day (called excessive daytime sleepiness) or sleep longer than usual at night
Insomnia
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
Melatonin
a hormone that your brain produces in response to darkness
Napping
short and meant to give you a bit of rest
Narcolepsy
a chronic neurological disorder that affects the brain's ability to control sleep-wake cycles
Night Terrors
Episodes of screaming, intense fear, and flailing while still asleep, often paired with sleepwalking
Nightmares
Frightening dreams, usually during REM sleep, that are normal and common in children under 10 and can also affect teens and adults.
Parasomnia
occur in a state that lies between sleep and wakefulness
Restless Legs Syndrome
typically occurs while sitting or lying down. It generally worsens with age and can disrupt sleep
Sleep
a state of reduced mental and physical activity in which consciousness is altered and sensory activity is inhibited to a certain extent
Sleep apnea
A potentially serious sleep disorder in which breathing repeatedly stops and starts.
Sleep deprivation
means you're not getting enough sleep
Sleep paralysis
a temporary inability to move or speak that occurs directly after falling asleep or waking up
Sleep study
a test that records the activity of the body during sleep
Snoring
Hoarse or harsh sound from nose or mouth that occurs when breathing is partially obstructed while sleeping.
Stage 1 (Non-REM) sleepw
the first sleep stage you enter when nodding off
Stage 2 (Non-REM) sleep
still light sleep, but deeper than stage 1.
Stage 3 (Non-REM) sleep
known as N3 or deep sleep
Stage 4 (REM Sleep)
your voluntary muscles become immobilized
Somnambulism
The act of getting up and walking around while asleep.
Wakefulness
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.