Chronobiology is the study of cyclical patterns of behavior and physiology in organisms. Humans are very familiar with daily rhythms like our sleep/wake cycle. Scientists refer to these daily changes as circadian (which means “about a day” in Latin). Most mammals have roughly 24 cycles in their metabolism rates which are reflected in changes like body temperature (see figure below), wakefulness, and hunger.
The daily behavioral rhythms we observe in organisms result from an interplay between internal physiological processes called biological clocks and external cues from the environment. Changes in either endogenous (internal) processes or exogenous (external) stimuli can disrupt circadian rhythms. If you’ve ever experienced jet lag then you know first hand that conflicts between internal and external cues can have severe effects on an organism!
Here at the museum, Wendy the woodchuck is about to go to sleep for the winter. Hibernation is an example of a biological cycle that occurs over a much longer scale than the circadian rhythms we just discussed. Because hibernation happens just once a year it would be classified as a circannual rhythm (Latin for “about a year”).
Want to learn more?
Dr. Matthew Andrews at the University of Minnesota is currently studying the genetics of hibernation in mammals. He did some of his ground breaking research at NC State before moving north.