Sleep

REM sleep

Active stage of sleep during which your breathing changes, your heart rate and blood pressure rise, and your eyes dart around rapidly

Sleep deficit

Condition that occurs when people frequently get less sleep than they should

Delayed sleep phase syndrome (DSPS)

Condition that results from a delay in the sleep-wake cycle that affects a person's daily activities

Narcolepsy

Disorder that affects the brain's ability to control the sleep-wake cycle

Jet lag

Fatigue that people feel after changing time zones when they travel

Melatonin

Hormone that increases feelings of relaxation and sleepiness and signals that it is time to go to sleep

Circadian rhythms

Naturally occurring physical, behavioral, and mental changes in the body that typically follow the 24-hour cycle of the sun

Sleep-wake cycle

Pattern of sleeping in a 24-hour period

Short Sleepers

People who can function well on less sleep than other people

Sleep apnea

Potentially serious disorder in which a person stops breathing for short periods of time during sleep

Sleep-wake schedule

Routine for going to bed at about the same time each night and getting up at about the same time each morning

Caffeine

Substance that increases energy, alertness, and attention, making it difficult to sleep

Parasomnia

Term for sleep disorders that occur when people are partially, but not completely awoken from sleep

Sleep Deprived

Term used to describe a person who gets inadequate amounts of sleep

Insomnia

Trouble falling or staying asleep

Blue light

Type of light from many digital devices, such as phones tablets, televisions, and computers, that produces large amounts of energy