Because their systems are less able to burn fat for energy, night owls may be more susceptible to heart disease and diabetes than early birds, according to US experts.
The researchers discovered that early risers rely more on fat as an energy source and are frequently more active during the day than those who go to bed later. This suggests that night owls may have an easier time storing fat.
The research may shed light on why night owls are more likely to develop type 2 diabetes and cardiovascular disease and may aid medical professionals in spotting patients who are more likely to do so in the future.
“This could help medical professionals consider another behavioral factor contributing to disease risk,” said Prof Steven Malin, a senior author on the study and expert in metabolism at Rutgers University in New Jersey.
On the basis of their responses to a questionnaire about their sleeping and exercise habits, the researchers separated 51 obese middle-aged adults into early risers and night owls. For a week, they observed the participants’ daily routines and assessed the fuel preferences of their bodies both at rest and when engaging in low-, moderate-, and high-intensity treadmill exercise.
The group’s findings are detailed in an article published in Experimental Physiology. They show that early risers were more responsive to blood levels of the hormone insulin and burnt more fat both at rest and during activity than night owls. The bodies of the night owls were less insulin-sensitive and preferred carbohydrates over fat as an energy source.
When compared to early birds, “night owls are reported to have a higher risk of obesity, type 2 diabetes, and cardiovascular disease,” he noted. “One explanation is that they misalign with their circadian cycle for a variety of reasons, with work being the most significant among adults.”