Repeated Challenge of Insufficient Sleep: Endothelial Effects

The 24-hour-a-day, 7-day a week, work-world arrived within our lifetimes, and is here to
stay. Americans are working more and more, frequently at multiple jobs. The pattern of short
sleep during the week followed by attempts to recover on the weekend is in common practice,
but we know little of the associated health risks. What is the cost in terms of increasing
known risk markers for cardiovascular disease, of repeated nights of insufficient sleep, and
is this cost compounded with repetition, without adequate recovery? Evidence is accumulating
to suggest that short sleep duration is linked to the development of metabolic and
inflammation-associated diseases, such as cardiovascular disease. Mechanisms involved in the
development of cardiovascular disease include impaired vascular function and inflammation.
The current proposal is designed to investigate the effects of repeated periods of short
nocturnal sleep duration in 4 cycles (each cycle consisting of 3 nights of 4 hours of sleep
opportunity per night), and each cycle of short sleep followed by a single night of recovery
sleep. Vascular reactivity will be assessed using brachial artery flow mediated dilation, and
microcirculatory vasodilation will be assessed using perfusion imaging techniques. The
dependence of IL-6 and sVCAM-1 as measured in peripheral circulation, on vascular function,
will also be investigated.