Tuesday, 29 May 2012

Is “Social Jetlag” making you fat?

If you love sleeping until noon over the weekends you might want to re-think your habits once you read this blog...

According to a study published this month in the journal Current Biology, researchers from the Universities of Munich and Groningen have shown that people with different sleep schedules on working days and free days (what the researchers called Social Jetlag) had triple the chances of being overweight.

Social jetlag is "the discrepancy between what our body clock wants us to do and what our social clock wants us to do," says Till Roenneberg, a professor at the University of Munich's Institute of Medical Psychology, in Germany. "It almost looks as if people on a Friday evening fly from Paris to New York, and on Monday morning they fly back again.”

Roenneberg and colleagues have surveyed the sleep habits of more than 65.000 European participants, comparing their sleep duration, sleep timings and patterns over working days and free days. They have found out that the Body Mass Index (BMI) of overweight people tended to be higher in those with a bigger discrepancy of sleep between their biological and social clocks (sleep discrepancy did not explain variations in body mass among those with a normal BMI).

These results confirmed previous data that linked higher BMI to sleep deprivation and irregular sleep schedules. Particularly, various studies have found an increased risk of obesity, as well as chronic diseases such as diabetes, among shift workers.

Some of the proposed explanations for the link between shift work and obesity, such as irregular meal times and metabolism disruptions, may help explain these social jetlag findings as well, Roenneberg says. "With social jetlag, we're forced to eat at times when the body doesn't want to eat, or isn't prepared for digesting food properly," he says. "All these things coming together might influence the way you digest food and how you incorporate it into your body fat. The result is that you become overweight or obese."

This study also explained why “teenagers show the largest discrepancy in sleep duration between free days and workdays”. Amongst other obvious reasons (such as playing computer games until late or chatting on their computers/mobiles :0)) this is because developmental changes in their circadian clock are not matched by the school start timings, changes particularly evident and fundamental at this phase.

So what can we do?
Adjusting our sleeping patterns isn’t easy. We just can’t simply rely on our biological clocks to wake up, we have work schedules to keep up to but paying more attention to our body clocks may be good start.

And here goes a link if you want to do a check-up to your sleep

Let's give this a thought, shall we?