Your Alarm Clock May Be Hazardous to Your Health
Switching up your sleep schedule is wreaking havoc on your body’s natural rhythm
- By Claudia Kalb
- Smithsonian magazine, January 2013, Subscribe
One overlooked culprit in the world’s obesity epidemic may be the alarm clock, according to Till Roenneberg, a professor at the University of Munich’s Institute of Medical Psychology.
He studies “social jet lag,” a term he coined, perhaps not surprisingly, on an airplane. But unlike the jet lag you get from shifting time zones, social jet lag is the chronic clash between what our bodies need (more sleep) and what our lives demand (being on time). And his research suggests that it’s playing havoc with our biological clocks.
In a study, published in May, Roenneberg and colleagues analyzed the sleep habits of more than 65,000 adults. Two-thirds of them suffered from social jet lag, experiencing at least a one-hour disparity between how long they slept on workdays and weekends.
The researchers also found that, over the past decade, people have been going to bed later but still getting up at the same time, losing about 40 minutes of sleep on workdays. They are also spending less time outside, which could account for why their circadian rhythms have become so late.
Previous studies have linked sleep deprivation with excessive weight, but Roenneberg’s team concludes that it isn’t just how much sleep people get that matters—it’s how much they mess with their internal clocks. For every hour of social jet lag accrued, the risk of being overweight or obese rises by about 33 percent. Obesity results from a host of influences, but Roenneberg says “one contributing factor is not living according to your biological temporal needs.” No one knows the precise mechanism, but other studies suggest that lack of sleep causes higher secretions of ghrelin, the appetite hormone, and a reduction of leptin, the satiety hormone.
Our daily lives are controlled by two naturally occurring phenomena: our internal circadian clock and the rotation of the earth. The hub of the body clock resides in a bundle of nerves called the suprachiasmatic nucleus, in the brain’s hypothalamus. This central clock acts as a pacemaker, synchronizing other cellular clocks that scientists believe exist throughout the body. This circadian clock system controls a variety of functions, including body temperature, hormone secretion and blood pressure. It also regulates the daily activities of organs.
The circadian clock must be rewound every day to keep it operating on a cycle of roughly 24 hours. It is reset by sunlight and darkness, the signals traveling to the brain through the optic nerve. Into that elaborate finely tuned natural system bursts the alarm clock.
Sleep is often viewed as an indulgence. But Roenneberg warns that people who sleep for fewer hours are not as efficient at their jobs, which creates a vicious cycle of working more and sleeping less. “Sleep has not been put out there by evolution as a time when we’re lazy,” he says. “ It’s a time when we’re preparing to be extremely active.”
Roenneberg doesn’t set an alarm clock unless he has to catch a plane, and he feels great. “I go through 16 hours without feeling a yawn,” he says.
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Comments (8)
Interesting article by another Kalb who is in Journalism... BK, David
Posted by David on February 1,2013 | 01:25 PM
Eye opening article. First let me try to make the alam bell more pleasing rather than disturbing and the slowly stop using alarm clock.
Posted by Karthikesan Sabapathy on January 3,2013 | 07:22 AM
vyctorynotes.blogspot.com says: I really liked this article. Is the "internal circadian clock" the same for wymin and men? When I have spoken with couples, it seems that men rise earlier in the morning. Is the "internal circadian clock" the same for those who are overweight, obese or morbidly obese? In other words, do we need more sleep the heavier we become?
Posted by Vyctorya on December 31,2012 | 08:01 PM
I would like it if the U.S. culture put more value on sleep. For me, getting 8+ hours per night is important for my focus, creativity and overall productivity at work. Plus I am just happier, and operating at my best. It's just not something most work places will flex on, so many come into work sleep deprived, yet right on time.
Posted by Sarah on December 31,2012 | 11:33 AM
The article is factual, but the blame is misplaced. It's not the alarm clock or waking up early that's the problem. It's staying up too late. It's okay to wake up at 6:00 am if you have fallen asleep by 10:00 pm. It' okay to wake up at 5, if you have fallen asleep by 9pm. Remember the old saying, "Early to bed, early to rise, makes a man healthy and wise." A lot of those old sayings are grounded in truth. When we burn the candle at both ends, we pay the price. Answer: turn the TV, computer, tablet, and smartphone off earlier. Unplug and read something for 15 to 30 minutes before bedtime. And set a goal for going to sleep. Sometimes when I am extremely busy I will set my alarm for a certain time at NIGHT so that it will go off and remind me that I need to quit working and go to bed. I might hit the snooze once or twice, but after that, I turn everything off and make myself go to sleep. Happy Dreams!
Posted by Scott on December 31,2012 | 11:24 AM
Great for Ronnerberg that he doesn't use an alarm, but for most of us that attitude would get us fired. How about some useful information like how much sleep do we need to get to not have Social Jet Lag? And how does he account for morning people?
Posted by Joey on December 31,2012 | 11:23 AM
"Switching up"? What's wrong with "switching"?
Posted by Manalto on December 30,2012 | 05:14 PM
My husband and I have been admirers of EuClock's research for many years. And as a result, we have become citizen scientist researchers per http://TrueTyme.org. So thank you very much for your hugely important article about social jet lag. As our Better Tymes For Women and our Better Tymes projects seek to help urban-dwellers (and especially women who work in windowless environments) be more aware of the passages of sun and moon time, we hope that you and some of your many readers will visit http;//TrueTyme.org to learn about what we are doing - and how? And then perhaps some of them will do their own "sample size of one" self-science research. Warmest regards, Jackie and Yale Landsberg, Cville VA Better Tymes For Women & The Better Tymes Project
Posted by Jackie Landsberg on December 29,2012 | 12:39 PM