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How Sleep Is Affected by Time Changes

What Difference Could an Hour Make?
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WebMD Feature

The daylight-saving time change will force most of us to spring forward and advance our clocks one hour. This effectively moves an hour of daylight from the morning to the evening, giving us those long summer nights. But waking up Monday morning may not be so easy, having lost an hour of precious sleep and perhaps driving to work in the dark with an extra jolt of java. How time changes actually affect you depends on your own personal health, sleep habits, and lifestyle.

Moving our clocks in either direction changes the principal time cue -- light -- for setting and resetting our 24-hour natural cycle, or circadian rhythm. In doing so, our internal clock becomes out of sync or mismatched with our current day-night cycle. How well we adapt to this depends on several things.

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In general, "losing" an hour in the spring is more difficult to adjust to than "gaining" an hour in the fall. It is similar to airplane travel; traveling east we lose time. An "earlier" bedtime may cause difficulty falling asleep and increased wakefulness during the early part of the night. Going west, we fall asleep easily but may have a difficult time waking.

How long will it take you to adapt to time changes? Though a bit simplistic, a rule of thumb is that it takes about one day to adjust for each hour of time change. There is significant individual variation, however.

How will you feel during this transition? If you are getting seven to eight hours of sound sleep and go to bed a little early the night before, you may wake up feeling refreshed. If you are sleep-deprived already, getting by on six hours, you're probably in a bit of trouble, especially if you consume alcohol or caffeine close to bedtime. In this situation, you may well experience the decrements of performance, concentration, and memory common to sleep-deprived individuals, as well as fatigue and daytime sleepiness.

What can you do to reset your internal clock to adapt more quickly to the time changes? Your circadian rhythm is internally generated but is influenced by the environment, behavior, and medications.

  • As mentioned, light is the principal environmental cue. Light suppresses the secretion of the sleep-inducing substance melatonin. So it is important to expose yourself to the light during the waking hours as much as possible, and conversely, do not expose yourself to bright light when it is dark outside. For example, if you get up at night to go to the bathroom, do not turn on the light. Prepare beforehand by installing a night light. Interestingly, specifically timed light therapy may either advance or delay your sleep cycle, depending on when it is delivered.
  • Sleep hygiene is a term used to describe those actions you can take to create sleep-friendly environments and enhance your chances of falling asleep, staying asleep, and sleeping soundly. Basic sleep hygiene includes reducing or eliminating caffeine and alcohol, exercising several hours before bedtime, creating calming rituals before bed to gradually relax yourself (taking a hot bath for example), and wearing ear plugs and eye masks, to name a few. Also important is going to bed and rising at the same time every day. Though there is no evidence that certain diets will actually influence your circadian rhythm, carbohydrates tend to make it easier to fall sleep.
  • It is unlikely that medications would be needed for a simple one-hour time change of the clock, but in certain circumstances, like traveling across multiple time zones, hypnotic drugs like bendodiazepines may be used. Their indication is primarily to induce sleep when desired, to get on a new schedule. Given their potential for addiction and that they can negatively affect the quality of sleep, they should only be used under the direct guidance of a doctor or sleep specialist.

So there may be some tired and groggy people hitting the streets Monday morning, in the dark. Interestingly, some studies show an overall reduction in traffic accidents and fatalities due to daylight-saving time changes. However, one study showed a significant increase in accident rates on the Monday following daylight-saving time. The author attributed sleepiness as a cause. I am not sure exactly which way to go on this one, but maybe you may want to just sit back and have another cup of coffee -- decaf, of course -- and go in to work a bit later, when the sun is up?

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You say you are able to function well with fewer than seven hours of sleep. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

Since you usually get too little sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have insomnia or other conditions affecting your sleep.

Sleep deprivation can have both short- and long-term consequences. Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's not surprising you feel that you're not functioning at your best today. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

Since you usually get too little sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have difficulty sleeping, have insomnia, or have other sleep disorders.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's not surprising you feel that you're not functioning at your best today. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

It's good that you usually do get more sleep, since sleep deprivation can have both short- and long-term consequences. Learn more about the health consequences of sleep loss. And if you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

You say you are able to function well with fewer than seven hours of sleep. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

It's good that you usually do get more sleep because sleep deprivation can have both short- and long-term consequences. Learn more about the health consequences of sleep loss. And if you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's not surprising you feel that you're not functioning at your best today. Some people say they can function on four to six hours of sleep each night, but research shows that adults who get fewer than seven hours of sleep — whether for just one night or over the course of days, weeks, or months — have more difficulty concentrating and more mood problems than people who sleep seven to nine hours.

Since you usually get less sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have difficulty sleeping or have insomnia or other sleep disorders.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's wonderful that you got a good night's sleep last night. Many people struggle to do so. Having a good sleep routine often is the key to getting the quality sleep night after night that your body needs for optimal health. Whether your sleep routine involves taking a warm bath, reading a book, or meditating, it's important to keep your bedtime and routine consistent every night and wake up around the same time every morning.

Click here to read more about the importance of sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's unfortunate you're not functioning at your best today. You say you had a good quantity of sleep last night, but maybe the quality of your sleep is not as good as it could be? Having a good sleep routine — including a consistent bedtime and wake time — often is the key to getting the quality sleep night after night that your body needs for optimal health. Since you usually sleep this amount, if you often aren't feeling your best, you should consider talking to your doctor. Could you have an underlying condition? Are you feeling anxious or depressed? Have you taken medication that disrupted your sleep? Do you or could you have sleep apnea? Or do you naturally require a little bit more sleep?

Although sleep is crucial for optimal health, some research suggests that sleeping too much can also have negative consequences. Learn more about sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's unfortunate you're not functioning at your best today. You say you had a good quantity of sleep last night, but maybe the quality of your sleep is not as good as it could be? Having a good sleep routine — including a consistent bedtime and wake time — often is the key to getting the quality sleep night after night that your body needs for optimal health. Since you usually sleep longer, if you often aren't feeling your best, you should consider talking to your doctor. Could you have an underlying condition? Are you feeling anxious or depressed? Have you taken medication that disrupted your sleep? Do you or could you have sleep apnea? Or do you naturally require a little bit more sleep?

Although sleep is crucial for optimal health, some research suggests that sleeping too much can also have negative consequences. Learn more about sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's wonderful that you got a good night's sleep last night. Many people struggle to do so. Having a good sleep routine often is the key to getting the quality sleep night after night that your body needs for optimal health. Whether your sleep routine involves taking a warm bath, reading a book, or meditating, it's also important to keep bedtime consistent and wake up around the same time every morning.

Although sleep is crucial for optimal health, some research suggests that sleeping too much can have negative consequences. Learn more about sleep. If you're concerned about having trouble falling asleep, staying asleep, or sleeping too much, assess your risk for a sleep disorder.

It's unfortunate you're not functioning at your best today. You say you had a good quantity of sleep last night, but maybe the quality of your sleep is not as good as it could be? Having a good sleep routine — including a consistent bedtime and waking up at the same time — often is the key to getting the quality sleep night after night that your body needs for optimal health.

Since you usually get less sleep, please talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have insomnia, another sleep disorder, or conditions affecting your sleep.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

It's wonderful that you got a good night's sleep last night. Many people struggle to do so. Having a good sleep routine often is the key to getting the quality sleep night after night that your body needs for optimal health.

Since you usually get less sleep, talk to your doctor about your sleep patterns. Poor quality sleep can affect many areas of your life and health, and your doctor may be able to help you if you have insomnia or another sleep disorder or conditions affecting your sleep.

Learn more about the health consequences of sleep loss. If you're concerned about having trouble falling asleep or staying asleep, assess your risk for a sleep disorder.

SOURCES:

Centers for Disease Control and Prevention (CDC). Effect of short sleep duration on daily activities--United States, 2005-2008. MMWR Morb Mortal Wkly Rep 2011; 60:239.

Carskadon, MA, Dement, WC. Normal Human Sleep: An Overview. In: Principles and Practices of Sleep Medicine, Fifth, Kryger, MH, Roth, et al. (Eds), Elsevier Saunders, St. Louis, MO 2011. p.16.

Harvard University: "Sleep, Performance, and Public Safety."

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