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The Science Behind Daylight Saving Time and Why You Feel Sleep-Deprived

03/25/2015 10:27 am ET | Updated May 25, 2015
Michelle McMahon via Getty Images

Daylight Saving Time is the first sign that spring is finally on its way. And while most of us look forward to the days staying lighter for longer, the time change can also have a major impact on your sleep.

Here's a look at why our natural circadian rhythms tend to make those first few days after DST so rough and the surprising ways that the time change could be putting your mood -- and health -- at risk.

How your circadian rhythm works

Babies aren't exactly known for being great sleepers. But as many a new parent can tell you, they seem to be especially bad at it during the first few months of life. But why?

It isn't because they're hungrier, or crankier, or have more diapers that need to be changed. Instead, it's because the infant brain has no concept of night or day. They've been used to a permanently dark environment, and sleeping and waking up whenever they feel like it. And when they first come into the world, it takes a little while to adjust.

But starting at around two months, they start to join the rest of us in knowing that light means it's time to be awake and lack of light means it's time to be asleep. Put more scientifically, they develop their circadian biological clocks.

Your circadian clock is responsible for regulating times of sleepiness and wakefulness throughout the day. Based largely on light exposure, it's controlled by a wing-shaped structure in the hypothalamus called the Suprachiasmatic Nucleus (SCN), which takes information from your eyes about whether it's light or dark and lets your body know whether it should feel awake or sleepy.

When your eyes tell your SCN that it's light out, the SCN works to rev you up by raising your body temperature and pumping out the stress hormone cortisol. When your eyes tell your SCN that it's dark, the opposite takes place. By lowering your body temperature and releasing a steady stream of the sleep hormone melatonin, you start to relax and feel tired.

How DST steals your sleep

Your circadian biological clock is responsible for telling your body when it's time to feel awake and when it's time to feel sleepy. And since it revolves around predictable patterns of light and darkness, any abrupt changes in your usual pattern of light exposure tends to throw it off.

It's a lot like the jet lag you'd experience if you flew from New York to London. Even though it might be 8 a.m. in London, you're exhausted because your body is still on New York time and thinks it's only 3 a.m. Your circadian rhythm will adjust to the cues from your new environment, but it takes a few days. In the meantime, you're zonked when you should be awake and energized when you should be asleep.

Since Daylight Saving Time only jumps ahead by one hour, most people don't expect it to have much effect. Maybe you wake up feeling a little more tired than usual the morning after you set your clock forward, but that's pretty much it. Right?

True, you'll definitely wake up feeling more tired. But the fatigue doesn't just last for a day, and its effects can be surprisingly far-reaching. More and more, research is showing that Daylight Saving Time has a more significant impact than most of us think.

According to the American Time Use survey, people wake up earlier in the morning and sleep about 20 minutes less at night once DST kicks in. The lack of sleep can actually leave you feeling groggy for days, and has been shown to cause a 6 percent increase in car accidents that continues for almost a week after springing forward.

And as any insomniac can tell you, too little shut-eye can mess with your mood. Which might be why one recent study found that people report feel less satisfied after Daylight Saving Time kicked in. The effect is particularly pronounced among people who work full-time, perhaps because they don't have the option to sleep in despite the fact that they're more tired than usual.

You're probably thinking, OK, so I might feel a little more tired, a little more crabby, and a little less alert for the week. But then I'll adjust and get back to normal.

Ideally, yes. If your circadian clock can adjust to jet lag that spans multiple time zones, then it has to be able to cope with a time change of one measly hour. Except some findings suggests otherwise. In fact, one German study that tracked the sleep habits of more than 55,000 people found that most of us never totally adapt to Daylight Saving Time. Though the reasons aren't entirely clear, night owls seem to fare worse than people who naturally wake up early.

Tips for coping with the change

As more and more people are realizing the negative effects of Daylight Saving Time (aside from messing with your sleep, data shows it doesn't actually save energy), some groups have even started petitions to get the time change repealed. And who knows? Maybe our grandkids will have no idea what Daylight Saving Time is or why anyone would bother changing their clocks.

But for now? Regardless of how you might feel about DST, we're stuck with it. (Unless you live in Arizona, which doesn't participate.) And happily, there are ways to minimize the time change's effect on your circadian clock so you aren't walking around like a zombie for the rest of the month. A few to try:

  • Prep over a few days. Get a jumpstart on giving your body time to adjust by gradually going to bed 15 minutes earlier over the course of three or four nights.
  • Take advantage of the power nap. If you're out of it in the afternoon, take a 20 minute snooze. It's long enough to leave you feeling refreshed, but not so long that you'll have a hard time falling asleep later.
  • Exercise, always. Several studies have shown that regular exercisers tend to sleep better than sedentary folk. Plus, now that it's lighter out later, you really have no excuse.
  • Make eight hours of sleep a priority. Most of us are already suffering from chronic lack of sleep, meaning DST simply makes an existing problem that much worse. By getting eight hours of sleep every night, you're guaranteed to feel more energized -- no matter what the clock says.

How did you handle DST this year? Do you usually have more trouble springing forward or falling back? Share in the comments.

Firas Kittaneh is the CEO of Amerisleep, an eco-friendly luxury mattress company. Firas writes more posts on the Amerisleep blog about getting better sleep, healthy living and being eco-friendly. Follow him on Twitter.