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A new study published in the Journal of Clinical Endocrinology and Metabolism examined the health difference between what researchers call “evening and morning chronotypes” — people whose natural sleep-wake cycles make them either night owls or morning people. The aim was to see whether staying up late affected metabolism and body fat, regardless of how many hours of sleep the person got after finally going to bed.
Sorry, night owls, but the results are not encouraging.
“Regardless of lifestyle, people who stayed up late faced a higher risk of developing health problems like diabetes or reduced muscle mass than those who were early risers,” study co-author Nan Hee Kim, M.D., an endocrinologist at Korea University College of Medicine, said in a news release.
“This could be caused by night owls’ tendency to have poorer sleep quality and to engage in unhealthy behaviors like smoking, late-night eating and a sedentary lifestyle,” Kim added.
Furthermore, those health risks stayed the same even when night owls got the same amount of sleep as the morning folks.
The study involved 1,620 adults ages 47 to 59, who answered questionnaires about their sleep habits and underwent tests to measure their blood glucose levels and body scans to measure fat and lean muscle mass. Based on the questionnaire results, 480 participants were classified as morning chronotypes, and 95 were categorized as evening chronotypes. The rest had a sleep-wake cycle between the two extremes.
Even though the night owls tended to be younger, they had higher levels of body fat and triglycerides (fats in the blood) than early risers — possibly because of all that late-night snacking. Couch potato night owls also had less muscle mass.
Men who were evening chronotypes were more likely to have diabetes and lower lean muscle mass than early risers. Among women, night owls tended to have more belly fat and a greater risk of metabolic syndrome, a cluster of symptoms that includes high blood pressure and elevated cholesterol that raise the risk of heart disease, stroke and diabetes.
The study does not prove that habitually staying up late is bad for your health — although a growing amount of research indicates sleep patterns can affect health — only that there appears to be an association between greater health risks and being a night owl.
As Kim told LiveScience.com, while a person’s wake-sleep cycle is affected by genetics, age, sex and sleeping environment, it can be modified by things like light, exercise and eating behavior.
To help move your body clock to an earlier bedtime, Kim suggested that night owls limit exposure to lights late at night and take melatonin, a natural chemical that helps people sleep.
