Being a night owl may not be a choice; after all, genes are known to influence our chronotypes, or the times we prefer to sleep and be active. But unfortunately, it seems that being an evening person could be detrimental to your health—and your waistline. According to a new study, night owls face a greater risk of developing diabetes and various other health problems, lending support to previous research that found that evening people are more likely to be obese than morning people.

Importantly, the findings also revealed that the differences between these groups of people are not simply down to the number of hours of sleep they are receiving, since the risks were the same in night owls who got equal amounts of sleep as early risers. The study has been published in the Journal of Clinical Endocrinology & Metabolism.

Although humans are generally diurnal, or active during the daytime, people display different preferences for when they sleep and do things. Some individuals prefer to go to bed late and are most functional during the night hours, whereas others like to get up early and are ready for action in the morning. While these patterns of sleep and activity might be partly down to our genes, unfortunately evidence has started to mount that being a night owl is associated with various health problems, such as an increased risk of being overweight or obese.

Interested in probing the potential health effects of different chronotypes further, scientists from the Korea University College of Medicine designed a study that aimed to investigate whether being a night owl is associated with metabolic abnormalities, such as diabetes. They enrolled 1,620 adult participants and asked them to fill in questionnaires about their sleep-wake cycles and lifestyle habits, such as smoking and exercise. Blood samples were then taken to assess metabolic health, and body scans were performed to measure body fat and muscle.

Based on the surveys, 30% of the participants were morning chronotypes, 6% were evening, and 64% were somewhere in the middle. Although those in the evening group tended to be younger, the results revealed that they also had more body fat and higher levels of fat in the blood than those in the morning group. Furthermore, regardless of how much sleep they got and other lifestyle factors, they were 3.2 times more likely to have a condition called sarcopenia, which is the gradual loss of muscle mass, and almost two times more likely to have Type 2 diabetes and metabolic syndrome, a cluster of symptoms that can lead to diabetes and heart disease.

According to the researchers, these differences could be due to the fact that night owls often have poorer sleep quality than morning people, and are also more likely to partake in unhealthy activities such as smoking and eating late.

Interestingly, the data also revealed a disparity between the sexes as male night owls were found to have a greater risk of diabetes and sarcopenia than early birds, but female evening chronotypes generally had more belly fat and a higher risk of metabolic syndrome.

It can be difficult to change sleeping patterns, especially since our biological clocks are determined by so many different things, but if people are concerned then it might be time to give the early bird thing a try.

[Via Endocrine Society, Journal of Clinical Endocrinology & Metabolism and Live Science]

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