A study recently published in the American Diabetes Association’s journal, Diabetes Care, suggests that high night-to-night differences in sleep schedules may be associated with higher risk of having metabolic syndrome (a cluster of health problems—including high blood pressure, low HDL cholesterol levels, high triglyceride levels, high blood sugar levels, and/or excess body fat around the waist—that increase risk for heart disease, stroke, and diabetes). The study assessed nighttime movements and sleep-wake cycles of over 2,000 participants for one week using home-based sleep studies.
Previous studies have found an association between sleep duration and metabolic syndrome, and experts like the National Sleep Foundation recommend adults get at least seven hours a night. This study focused on irregular sleep schedules, rather than just duration. It suggests that lack of consistency is an issue, no matter how well one sleeps on a given night, or for how long. Participants whose sleep duration varied by 60 to 90 minutes per day were 27 percent more likely to have metabolic syndrome compared to those who had less than one hour variation. This difference rose to 57 percent for those with more than two hours per day of variation in sleep duration. Varying bedtime by more than an hour was also associated with higher risk of having metabolic syndrome. To avoid irregular sleep schedules (and possibly lower risk for health problems) set a consistent bedtime; sleep in a dark room; turn phones, TVs, and other electronics off; and avoid large meals, caffeine, and alcohol before bedtime.