Chronotype

A chronotype is the behavioral expression of a person's underlying circadian rhythm, reflecting an individual's natural tendency to be alert, and to want to sleep, at particular times within a twenty four hour cycle. Chronotypes fall along a spectrum between two extremes: eveningness, in which alertness peaks in the evening, and morningness, in which it peaks in the morning, with most people falling somewhere between the two. The typical chronotype shifts over the course of a lifetime: children tend to prefer earlier sleep and waking times, adolescents typically shift toward later ones, and many older adults drift back toward earlier preferences again. Chronotype research now extends well beyond humans, with comparable individual differences in circadian timing documented in species such as fruit flies and mice. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/