The study was conducted with 1,600 participants from South Korea, aged between 47 and 59, of whom 95 were late sleepers or night owls, while 480 were early risers. The rest fell somewhere in between. The participants shared details of their sleeping habits and were put through tests to assess health.
“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,” co-author, Dr. Nan Hee Kim said. Kim works at the Korea University College of Medicine in Ansan, South Korea. “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,” he added.
Earlier studies had established that late-sleepers might actually be more creative, mentally alert, and might have higher IQs than early risers. However, the time of sleep was also found to have different effects on different parts of the brain.
Despite the fact that the late sleepers were on average younger, they had more body fat and fats in the blood as compared to early risers. Men who were late sleepers were also at greater risk of diabetes, and sarcopenia, where the body gradually loses muscle mass.
Women who were late sleepers were likely to have more belly fat and a higher risk of metabolic syndrome, a set of conditions that raises the possibility of diabetes, heart disease and stroke.
Though the study found a correlation between late-sleeping habits and health problems, it has not established a cause and effect relationship. However, Kim cautioned, “Considering that many younger people are night owls, the risk associated with this type of sleep habit is an important health issue that needs to be addressed.”
The study titled, “Evening Chronotype Is Associated With Metabolic Disorders and Body Composition in Middle-Aged Adults” was published in April in the Journal of Clinical Endocrinology & Metabolism.
