A pair of researchers at the University of Pennsylvania has been analyzing papers by researchers studying the circadian rhythm in humans and has found a pattern: there are gender differences. Seán Anderson and Garret FitzGerald have published a Perspective piece in the journal Science describing the differences they found.
Prior research has found that humans and other animals have more than one kind of bodily rhythm. In addition to the circadian rhythm, which regulates sleep and wakefulness, humans have rhythms that control breathing, the shedding of skin and the heart rate—to name just a few. The circadian rhythm is perhaps the most well-known because it has such an observable impact on our daily lives; it controls when we go to bed and when we wake up. It also is involved in metabolism. We get more tired at certain times than others and because of that, tend to speed up or slow down whatever it is we are doing. In this new effort, the researchers were looking to learn more about the circadian rhythm by reading papers written by researchers who had conducted direct studies of its impact on people. In all Anderson and FitzGerald looked at studies involving over 53,000 people. In so doing, they found that age and sex “substantially affect” body clocks.