Circadian rhythm
the natural, roughly 24-hour cycle of physical, mental, and behavioral changes that occur in living organisms, primarily regulated by light and darkness, and influencing sleep-wake cycles, hormone release, and other bodily functions
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
a condition where individuals experience a persistent and overwhelming urge to sleep, even after getting adequate rest at night.
Insomnia
habitual sleeplessness; inability to 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 condition characterized by an extreme tendency to fall asleep whenever in relaxing surroundings.
Night Terrors
a type of sleep disorder characterized by episodes of intense fear, panic, and often screaming or thrashing during sleep, occurring during non-rapid eye movement (NREM) sleep, typically in the first part of the night.
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 neurological disorder characterized by an irresistible urge to move the legs, often accompanied by uncomfortable sensations, that worsens at rest, especially in the evening and at night.
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 or periods of shallow breathing during sleep,
Sleep deprivation
the condition of not getting enough sleep, or being prevented from having enough sleep
Sleep paralysis
a temporary inability to move or speak, often occurring as you're falling asleep or waking up, while remaining fully conscious,
Sleep study
an overnight diagnostic test that monitors and records various body functions while a person sleeps to help diagnose and treat sleep disorders.
Snoring
the action or fact of making a snorting or grunting sound while asleep.
Stage 1 (Non-REM) sleep
the first sleep stage you enter when nodding off
Stage 2 (Non-REM) sleep
a stage of light sleep, deeper than Stage 1, characterized by slowed heart rate, breathing, and body temperature, with brain waves showing a new pattern and eye movements ceasing.
Stage 3 (Non-REM) sleep
the deepest stage of Non-REM sleep, characterized by slow, high-amplitude delta waves, making it difficult to wake someone from, and is crucial for restorative processes like tissue repair and immune system strengthening.
Stage 4 (REM Sleep)
the final stage of the sleep cycle, characterized by rapid eye movements, increased brain activity (similar to wakefulness), and temporary muscle paralysis, where most dreaming occurs.
Somnambulism
sleepwalking.
Wakefulness
the state of being awake, conscious, and alert, as opposed to being asleep, where an individual is able to engage in coherent cognitive and behavioral responses to the external world.