Impact of Chronic Circadian Disruption vs. Chronic Sleep Restriction on Metabolism

It has long been recognized that sleep patterns change with age. A common feature of aging is the advance of the timing of sleep to earlier hours, often earlier than desired. These age-related changes are found in even healthy individuals who are not taking medications and who are free from sleep disorders. In addition to these sleep disturbances, many older individuals curtail their sleep voluntarily, reporting similar rates of sleep restriction (sleeping less than 7 or less than 6 hours per night) when compared to young adults. Whether voluntary or not, insufficient sleep has medical, safety and metabolic consequences. In fact, converging evidence in young adults suggests that sleep restriction per se may impair metabolism, and that reduced sleep duration is associated with weight gain, obesity, diabetes, cardiovascular disease, and mortality. An understanding of how the circadian and sleep homeostatic neurobiological processes responds to increasing homeostatic sleep pressure, and the effects of sleep restriction on metabolism at different ages, should provide information on the regulation of sleep and metabolism in aging, as well as direction for future treatments. In the present study, we will study the separate impacts of chronic sleep restriction (while minimizing circadian disruption) and chronic circadian disruption (while minimizing sleep disruption) and a poor diet on metabolism.