A bedtime is a popular parenting tradition in the West that involves, to a greater or lesser extent, rituals made to help children feel more secure, and become accustomed to a comparatively more rigid schedule of sleep than they would sometimes prefer. It may involve stories, songs, nursery rhymes, and/or methods of coaxing the children into changing into their pajamas.
In boarding schools and on trips or holidays that involve young people, the equivalent of bedtime is lights-out.
Sometimes the term is used to mean simply"time for bed," similar to curfew.
A circadian rhythm is an approximate daily periodicity, a roughly-24-hour cycle in the biochemical, physiological or behavioural processes of living beings, including plants, animals, fungi and cyanobacteria. The term"circadian", coined by Franz Halberg, comes from the Latin circa,"around", and diem or dies,"day", meaning literally"approximately one day." The formal study of biological temporal rhythms such as daily, tidal, weekly, seasonal, and annual rhythms, is called chronobiology.
Circadian rhythms are endogenously generated, and can be entrained by external cues, called Zeitgebers. The primary one is daylight. These rhythms allow organisms to anticipate and prepare for precise and regular environmental changes. |