Association of Sleep Time With Diabetes Mellitus and Impaired Glucose Tolerance

Abstract

The usual amount of sleep per night has been declining among US adults for more than a generation. The median sleep time in adults aged 40 to 79 years was 8 hours per night in 1959, with less than 15% reporting a usual sleep time of less than 7 hours.¹ By 2002, the adult median sleep time had decreased to 7 hours per night, with more than one third of adults sleeping fewer than 7 hours.² Although insomnia is highly prevalent, much of the reduction in sleep time reflects voluntary sleep restriction, with 43% of adults reporting that they often stay up later than they should watching television or using the Internet and 45% reporting that they sleep less to get more work done.³ Several studies have found increased mortality associated with usual sleep times of less than 7 or more than 8 hours per night.^4-7 Experimental restriction of sleep to 4 hours per night for 6 nights resulted in impaired glucose tolerance (IGT) in healthy young adults.⁸ Because diabetes mellitus (DM) carries a high risk of cardiovascular-related mortality, the impact of sleep restriction on glucose regulation suggests a mechanism whereby short sleep time might increase mortality. In the present study, we examined the relation of self-reported usual sleep time to prevalent DM and IGT in a large community-based sample of middle-aged and older adults.