1. Age: older people run cooler. Our metabolism slows as we age and our body’s not as active, so uses less energy, says Waleed Javaid, an infectious disease doctor at West Virginia University.
2. Gender: women are warmer than men. Even outside menstrual cycle spikesin elderly women, body temperatures are higher, says Parsonnet. Scientists don’t really know why this is the case, she adds; “we just have a different setting.”
3. Time of Day: the early morning dip. “Temperature has a circadian rhythm,” says rheumatologist Jonathan Hausmann at the Boston Children’s Hospital and Massachusetts General Hospital, who’s recent study observed a dip from 03:00-05:00 and a peak between 16:00-18:00. Probably reflecting increased activity during the day.
4. Height and weight: one lowers, the other raises. Body temperature declines with height because more surface area loses more heat, whereas temperature goes up a little bit with weight, explains Parsonnet.
Source: www.bbc.com
