Time change and body clocks

Time to set the clocks back once again!

After midnight this coming Sunday, our clocks will move backward by an hour. The purpose is to shift an hour of daylight from afternoon to morning over the winter months. About a quarter of the earth’s population will experience this changeover.

The clock says we gain an extra hour of sleep on Monday morning but our bodies don’t feel it. So the question is, what happens to our bodies’ internal clocks when they are suddenly reset to suit society?

Our circadian rhythm determines when we are sleepy and when we are awake and alert, when we want to eat and so on. Even though there are as many variations in this rhythm as there are people on the planet, our internal clocks are mainly regulated by the sunrise. We are not aware of this fact, however, and our lovely, deep sleep is often rudely interrupted when the alarm clock rattles in our ears on a weekday morning.

Scientists studying this mystery of the circadian rhythm have compared awake times and sleep times on workdays and on weekends and have found that the midpoint between the moment you fall asleep and the moment of dawn remains constant even as sun-up changes with the seasons.

So what happens to our internal clocks when the external clocks jump forward or backward an hour? They found in a study of over 50,000 test subjects, that the normal sleep cycle is disrupted in the change-over from standard to daylight saving time. Was this disruption due to the changed clock or to some other unknown cause? They further tested 50 people and discovered that the institution of daylight-saving time disconnected the body’s sleep-wake pattern. When the clocks were returned to standard time, the circadian rhythm once more linked itself to the time of sunrise.

What does this mean in a practical sense? Well, it would seem that tinkering with our bodies’ own built-in wisdom really does have a not-so-good effect on our bodies, and I, for one, am glad to be getting back to good, old-fashioned winter time. That extra hour under the blankets sounds pretty good to me.

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