A recent study finds that night owls are more at risk for health problems such as diabetes, sarcopenia (a condition where the body gradually loses muscle mass), and metabolic syndrome (a collection of health conditions that increases the risk of diabetes, heart disease, and stroke). This is true even if the night owls sleep the same amount of hours as early risers.
The study included more than 1600 participants ranging in age from 47 to 59. These individuals provided information about their sleep habits and were categorized as either a night owl, early riser, or somewhere in the middle. The participants also underwent tests to evaluate their health.
Male late nighters were more likely to have diabetes or sarcopenia, while female night owls had an increase in belly fat and a higher risk of metabolic syndrome, in comparison to early risers. The study authors attribute this to the night owls poorer sleep quality and tendency to engage in unhealthy behaviors such as smoking, late-night eating, and sedentary lifestyle.
Source: Yu J, Yun C, Ahn J, et al. Evening chronotype is associated with metabolic disorders and body composition in middle-aged adults. The Journal of Clinical Endocrinology & Metabolism, April 2015; 100 (4): 1494-1502.