PSYB64H3 Chapter Notes - Chapter 11: Circadian Rhythm, Sleep Spindle, Seasonal Affective Disorder
Document Summary
A repeating cycle of about 24 hours. Biological clocks interact with zeitgebers to maintain these rhythms. Zeitgebers: an external cue for setting biological rhythms (light is the most important: examples: physical activity, feeding, body temperature, sleep-related hormones. Free-running circadian rhythms: a rhythm that is not synchronized to environmental time cues: runs for about 24. 2-24. 9 hours in the absence of natural light. Entrainment: the resetting of internal biological clocks to the 24 hour cycle of the earth"s rotation which is usually done by the exposure to sunlight. Sailors and blind people have free running cycles longer than 24 hours leading to sleep disruption. Individual sleep patterns result from different versions of the genes responsible for internal clocks. Regardless of normal lifetime sleep patterns, adolescents are usually owls (stay awake at night) Melatonin (neurochemical involved in sleep pattern regulation) levels drops at puberty onset: when neural systems mature, sleep patterns will go back to normal most of the time.
