News Review From Harvard Medical School -- Lack of Sleep May Fuel Insulin Resistance
Not getting enough sleep may change the way cells handle insulin, increasing people's risk of diabetes, a new study finds. Other research has linked a lack of sleep to a higher risk of obesity and diabetes. The new study looked at the effects of sleep on cells. It included 7 healthy young adults of normal weight. They were randomly assigned to sleep either 8.5 hours or 4.5 hours in a sleep lab for 4 nights in a row. Then everyone did the opposite sleep regime for another 4 nights. This took place 4 weeks later. After each 4-day cycle, researchers took samples of belly fat cells. After the sleep-deprived period, fat cells were 30% less able to respond to insulin. This is the hormone that helps move sugar (glucose) from the blood to other body cells. When cells "resist" insulin, the pancreas has to make more of it. And in this study insulin levels were nearly 3 times higher after people were sleep-deprived. If the pancreas can't make enough insulin, blood sugar stays up. This leads to type 2 diabetes. The journal Annals of Internal Medicine published the study. HealthDay News wrote about it October 15.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Not getting enough sleep is linked with higher body weights and an increased risk of developing type 2 diabetes. At first blush, you would think this doesn't make sense. During sleep, you tend to burn fewer calories than when you are awake. If you burn fewer calories, more of them will be stored as fat. So why would getting less sleep increase diabetes risk?
Experts have suggested that somehow sleep helps our bodies handle blood sugar efficiently. It seems they are correct. The results of this study offer a very good explanation of why not getting enough sleep increases your risk of type 2 diabetes.
Type 2 diabetes starts with insulin resistance. Insulin is the key hormone needed to keep blood sugar levels in the normal range. Insulin resistance means the cells in the body don't respond normally to the insulin made by the pancreas.
After we eat, blood sugar naturally starts to rise. The pancreas puts out a little extra insulin to assist the entry of sugar into cells. If you have insulin resistance, the pancreas needs to make and release higher levels of insulin into the blood to overcome the resistance.
Eventually, the pancreas can't make enough insulin to lower the blood sugar. First, there is pre-diabetes. If nothing changes, this goes on to the next stage: higher blood sugar levels and type 2 diabetes.
The results of this study are alarming. Getting 4.5 hours sleep vs. 8.5 hours sleep over just 4 nights resulted in 3 times higher insulin levels. The researchers also took samples of belly fat cells. The fat cells in the sleep-deprived people showed insulin resistance. Their fat cells were 30% less responsive to insulin than those of the well-rested folks.
This study included only a few people. So more research is needed. But as we seek reasons for the incredibly rapid rise in type 2 diabetes throughout the world, too little sleep could be one more important factor.
What Changes Can I Make Now?
This study did not look at sleep quality. But it's likely that is just as important as the amount of time you spend in bed.
Here are some ways to help you get better quality sleep:
- Establish a regular bedtime and a relaxing bedtime routine. Examples might include taking a warm bath or listening to soothing music.
- Use your bed only for sleeping or lovemaking. Avoid reading and 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.
- Get plenty of exercise. Build up to 45 minutes of moderate exercise nearly every day. Get your exercise early in the day. Try some easy stretching exercises or yoga to relax your muscles and your mind at bedtime.
- 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.
- Adjust what you eat and drink.
- Don't go to bed hungry, but don't eat a big meal right before getting into bed. If you want a bedtime snack, keep it bland and light.
- Limit caffeine and consume none after 2 p.m.
- To decrease middle of the night urination, don't drink any fluids after dinner.
- Avoid alcohol after dinnertime. Although many people think of it as a sedative, it can actually impair your sleep.
- Be sure your bed is comfortable and your bedroom is dark and quiet. Consider a sleep mask or earplugs. Don't let yourself get overheated. Keep the bedroom at a constant, comfortable temperature.
- Don't take long naps during the day. If you need a nap, restrict it to 20 to 30 minutes in the early afternoon.
- Turn the alarm clock around so you won't worry that you are still awake.
- Practice relaxation breathing. Use slow breaths, especially when you exhale.
What Can I Expect Looking to the Future?
This study does not prove that getting too little sleep increases the risk of type 2 diabetes. But these results add one more reason to make sleep a priority.