Source October 27, 2015

The end of Daylight Saving Time is just on the horizon, along with our annual panic over which clocks switch automatically and which are manual (how much do you know, microwave?). But beyond that low-level stress, it turns out Daylight Saving Time can impact our health in both positive and negative ways.

The extra hour of sleep we get when Daylight Saving Time ends in the fall is a major boon for our chronically sleep-deprived society, says Wayne Andersen, M.D., co-founder and medical director of Take Shape For Life.

But it's only great if you can actually sleep that extra hour. Those of us with less-than-stellar sleep habits (like taking long late-afternoon naps or scrolling through Instagram in bed) won't reap the same benefits, says Teofilo L. Lee-Chiong, Jr., M.D., a sleep expert and professor of medicine at the University of Denver. "In fact, many people don’t—or can’t—take advantage of the extra hour due to the body’s circadian clock, and may wake up earlier than usual," Lee-Chiong says.

If you're one of those people, you can blame the suprachiasmatic nucleus (SCN), which acts as our central clock and regulates our body temperature, digestion, hormone release, and sleep-wake cycles. The SCN is programmed to work around daylight, so when we try and artificially override it, we're not always successful.

Falling back also coincides with winter's shorter days, which can lead to an uptick in the number of people who suffer from seasonal affective disorder (SAD), Andersen says. "Research has shown that people with SAD feel better after exposure to bright light and greatly benefit from sunlight in the morning," Lee-Chiong says. "So during the fall and winter months, when we get less exposure to sunlight, it can be helpful for people with SAD to counteract the effects of lost sunlight with bright artificial light therapy."