Late to bed, early to rise: a recipe for diabetes

For most people, not getting enough sleep isn’t a big deal. So what if you aren’t as sharp as usual the next day, or feel a bit groggy? But sleeping poorly night after night—because you are trying to burn the candle at both ends or you work night or rotating shifts—has long-term health consequences. People who don’t average at least six hours of sleep a night are more likely to be overweight or develop various medical problems, including diabetes, as described earlier on the Harvard Health blog.

Being overweight is a big risk factor for becoming diabetic. Researchers long thought that the poor eating habits that went along with poor sleep were at the root of sleep-related diabetes. With the help of 21 volunteers who lived in a sleep lab for almost six weeks, researchers from Harvard-affiliated Brigham and Women’s Hospital have shown that lack of sleep plays an even more complex and powerful role.

Each of the volunteers followed a carefully scheduled daily program of eating, physical activity, and sleeping. They started out well rested, getting 10 hours of sleep a night for the first six nights. Over the next three weeks, they spent just 5.6 hours in bed each night, and it came later and later each day. The schedule was meant to mimic rotating shift work or extended jet lag.

This sleep pattern completely threw off the body’s sleep-wake rhythm, which influences the daily rise and fall of body temperature and blood pressure, and the secretion of many hormones.

During the three weeks of abnormal sleep, the participants’ bodies stopped releasing enough insulin after a meal. Muscles need this hormone to absorb sugar (glucose) from the bloodstream. As a result, their blood sugar levels went haywire. Some of the people had blood sugar levels high enough to have been diagnosed as prediabetic.

At the same time, the volunteers’ rates of metabolism slowed. Because they were eating a controlled diet, they did not gain weight. But if they had eaten as much as they did during the first few days of the study, when they were getting plenty of sleep, the researchers estimated the volunteers would have gained the equivalent of 10 to 12 pounds over a year. The results were reported in the journal Science Translational Medicine.

Improving sleep

We’ve known for some time that being overweight increases the risk of developing diabetes, as does lack of physical activity. This work reported in Science Translational Medicine, by Dr. Orfeu Buxton and his colleagues, offers a look at how poor sleep might lead to type 2 diabetes, the kind most likely to affect older individuals. Sleep troubles have also been linked to the development of high blood pressure, heart disease, and some cancers.

The U.S. Centers for Disease Control and Prevention estimates that up to 70 million Americans live with chronic sleep problems. Here are a few recommendations for getting more—or better—sleep:

• Establish a regular bedtime and a relaxing bedtime routine.
• Use your bed only for sleeping or lovemaking. Avoid reading or watching television in bed.
• If you can’t sleep after 15 to 20 minutes, get out of bed and go into another room. Read quietly with a dim light. Don’t watch television since the light from the TV has an arousing effect. When you feel sleepy, get back into bed. Don’t delay your scheduled wake-up time to make up for lost sleep.
• Whenever possible, schedule stressful or demanding tasks early in the day and less challenging activities later. This helps to wind down at the end of your day.
• Limit caffeine; to be on the safe side, don’t have any beyond midafternoon.
• Avoid alcohol after dinnertime. Although many people think alcohol acts like a sedative, it can actually disrupt your sleep.
• If you work nights, try wearing yellow- or orange-tinted glasses on the trip home. These block some blue light from reaching your eyes, which can wake you up. Go straight to bed when you get home.

Excellent information on sleep problems, and how to overcome them, is available from the online Sleep and Health Education Program, sponsored by Harvard Medical School’s Division of Sleep Medicine.