Sleep

Snoring is the vibration of respiratory structures and the resulting sound due to obstructed air movement during breathing while sleeping.

"Rip Van Winkle" is a short story by American author Washington Irving published in 1819.

An alarm clock (or sometimes just an alarm) is a clock that is designed to alert an individual or group of individuals at specified time.

A biorhythm (from Greek βίος - bios, "life" and ῥυθμός - rhuthmos, "any regular recurring motion, rhythm") is an attempt to predict various aspects of a person's life through simple mathematical cycles.

Hibernation is a state of inactivity and metabolic depression in endotherms.

A nightmare, also called a bad dream, is an unpleasant dream that can cause a strong emotional response from the mind, typically fear but also despair, anxiety and great sadness.

Rapid eye movement sleep (REM sleep, REMS) is a unique phase of mammalian sleep characterized by random movement of the eyes, low muscle tone throughout the body, and the propensity of the sleeper to dream vividly.

Night terror, also known as sleep terror, is a sleep disorder, causing feelings of terror or dread, and typically occurs during the first hours of stage 3-4 non-rapid eye movement (NREM) sleep.

Chronotype refers to the behavioral manifestation of underlying circadian rhythms of myriad physical processes.

A bedtime story is a traditional form of storytelling, where a story is told to a child at bedtime to prepare the child for sleep.

Memory is the cognitive process whereby experiences, learning and recognition are recalled.

Somnolence (alternatively "sleepiness" or "drowsiness") is a state of strong desire for sleep, or sleeping for unusually long periods (compare hypersomnia).