The British newspaper, The Guardian, quoted scientists who stated that people who wake up early depend more on fat as an energy source and tend to be more active throughout the day compared to those who stay up late. This means that fat may accumulate more easily in those who work at night, making them more susceptible to heart disease and type 2 diabetes.
Researchers divided 51 middle-aged obese adults into two categories, daytime and nocturnal, based on their responses to a questionnaire about sleep and activity habits. They monitored the volunteers’ activity patterns for a week and tested their bodies’ energy preferences both at rest and while performing moderate or high-intensity exercise on a treadmill.
“These findings could help clinicians consider another behavioral factor that contributes to disease risk,” said Professor Stephen Mallen, the senior author of the study and a metabolism expert at Rogers University in New Jersey. Mallen believes that it is not clear why differences in metabolism appear between the two groups, but one possibility is the mismatch between the time when people go to bed and the circadian rhythms that govern their body clocks. He added, “If we promote a timing pattern that is out of sync with nature, it may exacerbate the health risks.”