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Fall time change and its impact on sleep

Douglas Heriot

Sleep is key to maintaining good health, but what happens to the human sleep cycle when the clocks change in the fall?

This week on “Take Care,” we discuss the effects of fall time change on sleep. Dr. Lois Krahn is a psychiatrist and sleep researcher at the Mayo Clinic Sleep Disorder Center in Arizona.

There are two major factors that influence sleep. Humans have a body clock that runs on a 24-hour basis and can be set in different ways, helping us remain consistent day-to-day. In addition, the more we sleep the more rested we are.

Other factors effecting sleep include the timing of various activities throughout the day, including when we eat or exercise and how much light we are exposed to. All of these factors come together to help the body schedule sleep and wakefulness.

With the clock change, we’re asking our body to adjust to an hour difference all at once,” says Krahn. Because of this abrupt change, Krahn calls this adjustment a fundamentally unnatural task.

“It’s very interesting, there is traffic accident data from various continents, North and South America as well as Europe, that shows that the first week after we change our clocks there is a consistent spike in motor vehicle accidents,” says Krahn.

Krahn says that the most logical explanation for this increase in traffic accidents is that people aren’t quite adjusted to the new timing. While our bodies might physically be awake, someone might be a little foggy and less attentive, resulting in a slower reaction time than usual after the time change.

Different people have different reactions to the time change, but it does not take more than a week to readjust. Some people take only a day or two while other individuals, those with a very rigid inner clock, need to be careful for the first few days until they have adapted to the new schedule. Younger individuals, including young adults and middle aged adults, adapt more readily than senior citizens to the time change.

Time change occurring in the fall is generally less challenging to adjust to than the clock change in the spring.

“For most people it is easier to stay up later and sleep in later, so essentially gain an hour. There are few people for whom it’s difficult,” states Krahn.

In the days leading up to the time change it can be helpful to begin gradually delaying bed time and wakening time. According to Krahn, this makes the change less abrupt.

“I don’t think we pay enough attention to how lighting can enhance our health,” Krahn also says. After the time change, Krahn suggests increasing light exposure in the morning to help the new time frame stick within the first few days.

If you are interested in increasing light exposure, light in the blue range, white light that is on the blue end of the spectrum, is the most effective for helping us feel more awake and also helps with mood.