Circadian rhythm
the body's internal 24-hour clock that regulates the sleep-wake cycle
Dreams
a subjective experience that most commonly occur during REM sleep, and can be caused by the brain processing daily information, re-experiencing memories, or other random signals
Electroencephalograph (EEG)
a medical test that measures the electrical activity of the brain
Hypersomnia
a condition characterized by persistent, excessive daytime sleepiness, even after adequate sleep
Insomnia
a common sleep disorder characterized by difficulty falling or staying asleep
Melatonin
a hormone your body naturally produces to regulate sleep
Napping
a short sleep during the day that can boost mood, alertness, and productivity
Narcolepsy
a chronic sleep disorder characterized by excessive daytime sleepiness and sudden "sleep attacks" that significantly impact daily life
Night Terrors
episodes of screaming, thrashing, and panic that occur during deep sleep, causing the person to seem terrified but remain unresponsive to being woken
Nightmares
disturbing dreams that can cause feelings of fear, anxiety, or sadness, and often cause the sleeper to wake up
Parasomnia
a sleep disorder characterized by abnormal behaviors, movements, or experiences that occur during sleep or while transitioning between sleep and wakefulness
Restless Legs Syndrome
a neurological disorder causing an irresistible urge to move your legs, often accompanied by unpleasant sensations like crawling, bubbling, or aching
Sleep
a vital biological process that allows the body and brain to rest and restore, cycling through different stages including non-REM and REM sleep
Sleep apnea
a disorder where breathing repeatedly stops and starts during sleep, causing poor sleep quality and potential health complications
Sleep deprivation
occurs when an individual fails to get the amount of sleep that they need
Sleep paralysis
temporary inability to move or speak while waking up or falling asleep, often accompanied by terrifying hallucinations or a feeling of pressure on the chest
Sleep study
a medical test that records brain waves, heart rate, oxygen levels, and other body functions while you sleep
Snoring
the sound produced by vibrating tissues in the upper airway during sleep, caused by a partial blockage that restricts airflow
Stage 1 (Non-REM) sleep
the initial, light stage of sleep that transitions you from wakefulness to sleep
Stage 2 (Non-REM) sleep
a light stage of sleep where the heart rate and breathing slow down, the body temperature drops, and eye movements stop
Stage 3 (Non-REM) sleep
the deepest stage of sleep, where the body repairs and regenerates tissues, builds bone and muscle, and strengthens the immune system
Stage 4 (REM Sleep)
the deepest stage of sleep, where the body repairs and regenerates tissues, builds bone and muscle, and strengthens the immune system
Somnambulism
sleepwalking
Wakefulness
the state of being awake, alert, and conscious of one's surroundings