How Sleep Is Affected by Time Changes

Can One Hour Really Make a Difference?

This coming daylight savings time change will have us advance our clocks by one hour. This will move an hour of daylight from the morning to the evening which gives us those longer summer nights we love so much. The problem is what happens to us when we wake up Monday morning, which may not be so easy. The fact we have lost an hour of sleep and possibly driven to work in darkness may have something to do with it. But, more importantly, this time change can affect you, depending on your own personal health, sleeping habits and lifestyle.

What happens is that changing our clocks in either direction changes our body’s primary time cue: light. This affects our 24-hour natural cycle, or circadian rhythm. In doing so, our internal clock gets out of sync or mismatched with our current day-night cycle. Just how well our bodies adapt to this change depends on a few things:

In general, when we “lose” an hour in the spring, it’s more difficult to adjust to the new rhythm than “gaining” an hour in the fall. It is similar to airplane travel; when traveling east, we lose time. An “earlier” bedtime may cause difficulty falling asleep and increased wakefulness during the early part of the night. When traveling west, we fall asleep easily but may have a difficult time staying awake.

How long will it take you to adapt to time changes? A simple rule of thumb is that it takes about one day to adjust for each hour of time change. There are significant individual variations, however.

How will you fare during this transition? If you’re getting 7 to 8 hours of excellent sleep and go to bed a bit early the night before, you may wake up feeling pretty good. If you’re sleep-deprived alreay, getting by on just 6 hours of sleep, you may not feel as good. This is exacerbated by consuming alcohol or caffeine close to bedtime. You may experience lack of performance, memory and concentration you usually feel when sleep-deprived.
So, while your circadian rhythm is internally generated, it is influenced by the environment, behavior and medications. Here are a few things you can do:

  • As mentioned, light is the primary environmental cue. Light suppresses the secretion of the sleep-inducing substance melatonin. So it is important to expose yourself to light during waking hours as much as possible. On the other hand, avoid exposing yourself to bright light when it is dark outside. For example, if you get up at night to go to the bathroom, avoid turning on the light. You can prepare beforehand by installing a night light.
  • Sleep hygiene is a term used to describe those actions you can take to create a sleep-friendly environment 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, such as taking a hot bath for example and wearing ear plugs and eye masks. 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 are needed for a simple one-hour time change 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. However, 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.

Of course, while annoying, time change effects are usually temporary. And, with Daylight Savings Time in the Spring, at least you can look forward to those longer summer nights!