Night owls may be more prone to heart disease and diabetes than early birds because their bodies can’t burn fat for energy, US researchers say.
Early risers rely more on fat as an energy source and are often more active during the day than late risers, which means fat can be stored more easily in night owls, the scientists said.
“This may help clinicians understand other behaviors that contribute to disease risk,” said Professor Steven Malin, senior author of the study and an expert in metabolism at Rutgers University in New Jersey.
The researchers divided 51 obese middle-aged adults into early birds and night owls based on their answers to a questionnaire about sleep and activity habits. They monitored the volunteers’ activity patterns for a week and tested their body’s fuel preferences during rest and during moderate- or high-intensity exercise on a treadmill.
Writing in Experimental physiologyThe team notes that in the past, birds were more sensitive to insulin hormone levels and burned more fat at rest and during exercise than night owls. Night owls were less sensitive to insulin and their bodies preferred carbohydrates as an energy source instead of fat.
Malin says it’s not clear why the metabolic differences between night owls and early birds appear, but one possibility, he believes, is a mismatch between when people go to sleep and when they wake up the next morning, and the circadian rhythms that control their body clocks.
“Compared to early birds, night owls have a higher risk of obesity, type 2 diabetes and cardiovascular disease,” he said. “A possible explanation for the cause is that they are out of whack with their circadian rhythms for a variety of reasons, but it could be work, especially among adults.
If a person is a night owl, they may choose to sleep late but have to get up early to go to work or take care of the kids, which can force them out of sync with their body clock, he said. When you choose to sleep.
The findings may have implications for discussions around the health risks of night shift work and even changing the clock for daytime hours. “If we introduce a timing system that is not in sync with nature, it can exacerbate health risks,” Malin said. “Hopefully it will become clear in time whether dietary patterns or activities can help to weaken these factors.”