tory of Neuroendocrinology whose experiments with mice suggest that disrupting their circadian rhythms prompts weight gain and impulsive behavior. “Once that conductor is disrupted, it loses its ability to keep these other players in sync with each other. The organs and tissues are then not working as well together as they should be.”
50 to 60 hours per week,” Knutson says. “You want to have a life outside work, so you pay with sleep time.”
But the body keeps a very exact accounting of the hours needed for sleep. If we build up a sleep “debt” of an hour or two per night, Monday through Friday, we’re generally not going to be able to make it up in one weekend. We By remaining awake when our biological carry that debt and the burden of sleepiness clock says we should sleep, we risk scrambling forward, often not even realizing how sleep imthe alignment of the internal systems regulated paired we are. by our SCN — with terrible implications for our “Several studies have shown that after cuweight, among other things. mulative sleep deprivation, individuals are no “All the different organs that regulate me- longer able to recognize the degree of sleepitabolism have circadian rhythms,” says Phyllis ness under which they operate,” says Van CauZee, MD, PhD, professor of neurology and di- ter. “They think they’re OK, but when their perrector of the Sleep Disorders Center at North- formance is tested, they fail miserably.” western University. “And when they’re out of What we need, say some experts, is a new sync, it can expose one to changes in metabolism or to choosing inappropriate food or to eat- characterization of sleep — one that doesn’t regard it as a time when we just turn ourselves ing too much.” off. We need a new appreciation of slumber as Some researchers think late nights fueled a part of the environmental metronome guiding by bright lights and glowing computer and TV important cyclical functions in our body — funcscreens may trick our bodies into thinking we’re tions that affect our weight, our body chemistry, in a sort of perpetual summer — a high-activity our neurology and our overall well-being. time when our hunter-gatherer predecessors Most of us assume the routines of a lean would have been loading up on readily availlifestyle — like healthy meals and exercise — able carbohydrates in preparation for a long, are limited to our waking hours. But that point cold winter. of view leaves out the crucial dark side of our “Our ancestors’ sleep durations would have 24-hour cycle, when sleep prepares our bodbeen shorter in the summer,” says James ies and minds to function at their best on the Gangwisch, lead author of the Columbia study. following day. It ignores the fact that our bodAnd our caloric needs would have been far ies require adequate downtime to regulate sysgreater, he explains — both to fuel long days of tems that have a direct impact on whether we activity and to accumulate precious fat stores accumulate unwanted weight, or succeed in that would carry us through the cold season. evading it — now and over the long haul. Our modern reality is entirely different, of course. “Now,” notes Gangwisch, “we can have year-round fat deposition, preparing for a winter that never comes. It comes, of course, but we’re still warm and can get all the food we want and can still have short sleep durations because we have year-round light exposure.” Playing Catch-up There are plenty of reasons why we’ve grown so estranged from sleep — despite its obvious health implications. Chief among these is our tendency to work longer hours. “Instead of working 40 hours, people are often working