PSYC 375 Chapter Notes - Chapter 13: Intrinsically Photosensitive Retinal Ganglion Cells, Retinal Ganglion Cell, Retinohypothalamic Tract

• School: University of Calgary
• Department: Psychology
• Course: PSYC 375
• Professor: Simon Spanswick

Document Summary

Origins of biological rhythms biorhythm: inherent timing mechanism that controls or initiates various biological processes. Circannual yearly; ex. migratory cycles of birds. Ultradian less than a day; ex, eating cycles (1. 5-2 hours) Infradian more than a day; ex. menstrual cycle. Free-running rhythms: rhythm of the body"s own devising in the absence of all external cues. Underground bunker study days 4-20 = free-running rhythm, subjects allowed to control day and night length daily activity period shifts from 24 > 25-27 hours days 21-25 = normal light-and-dark cycle. Nocturnal animals constant darkness free-running periods are a little < 24 hours constant light free-running periods are a little > 24 hours. Diurnal animals constant darkness free-running periods > 24 hours constant light free-running periods < 24 hours (and are much more active throughout the testing period) Humans excess arti cial light = sleep periods contract.