Scaring the daylights out of our body clocks

We should all be feeling uncommonly rested after gaining an extra hour’s sleep after the switch from daylight saving time, but even after a week many of us probably aren’t.

Certainly, gaining an hour is easier to handle than losing an hour when daylight savings comes in. The Sleep Health Foundation says it can take up to a week to get back to feeling normal when we lose an hour.

But many of us will have eked out the extra hour staying awake rather than going to bed on time. And those of us who did go to bed probably woke up an hour early and spent the hour vainly ignoring the demands for breakfast from the dog, the cat or the kids who were blissfully unaware of the time shift.

So whichever way the clocks go during our shifts to and from daylight savings, we tend to feel out of kilter with a mild case of jet lag that will take a day or few to get over, says Dr Amy Jordan, University of Melbourne sleep expert at the Melbourne School of Psychological Sciences.

“In both transitions, whether you are gaining an hour or losing an hour, we end up with less sleep, probably for a few days,” Dr Jordan says.

The problem is that our circadian rhythms, our internal body clock, have been tuned through evolution to the movements of the sun rather than our modern obsession with ordering time around us.

“Circadian rhythms are the body’s internal rhythms that help us to have periods of rest and activity, to eat food at appropriate times and to keep our bodies on track,” she says.

Animals and plants are attuned to the sun in what Dr Jordan says is a biological adaptation that takes best advantage of the environment, whether it be daylight or night.

For example, heliotrope plants open their flowers in the daytime but close them at night to keep in heat and preserve energy. But if you put a heliotrope in a darkened room it will still open and close its flowers based on the 24-hour clock, even though it is in constant darkness.

minimising the damage

When the clocks change it is a matter of allowing time to get accustomed to it.

One of the causes of insomnia is going to sleep at irregular hours rather than listening to your circadian rhythms. So the best way to get over time shifts is to set a regular bedtime and try and stick to it within an hour or so, says Dr Jordan.

“Part of what helps us to sleep in the evening is that we have this circadian rhythm that is telling us that now is a good time to go to bed. If you are changing your sleeping time all over the place then the circadian drive towards sleep can get mucked up,” she says. “You can predispose yourself to some insomnia-type problems if you don’t keep a regular schedule.

“Getting to bed on time is good for you, but maybe not for your social life.”

Even a time shift of just one hour when the clocks change can cause problems if we aren’t careful. Dr Jordan points out that when we all change our clocks at the same time the problems can be magnified – such as a greater risk of road accidents. While the evidence is mixed, research in the US and Canada has found that clock changes for daylight saving are correlated with an increase in the number of car accidents.

There may also be potential health consequences from the stress we put on ourselves when we are short of sleep.

Some research in the US has found that daylight savings transitions are associated with a greater incidence of acute heart problems.

“Not all of the studies consistently show effects but certainly some studies have shown that the risk of suffering a heart attack is greater the Monday after the daylight savings change in the spring and that there are more fatal traffic accidents,” says Dr Jordan.

She recommends having a quiet weekend when the clocks shift to give you time to adapt. And a national get-to-work-late day on the Monday after might be a good thing too, she says.

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