September 6, 2013
News Review From Harvard Medical School -- Sleepy Shoppers Haul Home More Calories
Groggy grocery buying can make you fat. That's one possible conclusion from a new study. Researchers gave 14 normal-weight men about $50 each to spend on a morning shopping trip. This occurred after they had been sleep deprived the night before. They repeated the shopping excursion on the morning after a normal night's sleep. In each case, the men could choose any of 40 foods to buy. The list was evenly split between high-calorie and low-calorie items. They were supposed to spend most of the money. Before both trips, the men were given a hearty breakfast so they wouldn't be hungry. Men bought 18% more food, with 9% more calories, after being sleep deprived than after having enough sleep. The journal Obesity published the study online. HealthDay News wrote about it September 5.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Most people know it's a bad idea to shop for food when you're hungry. It's a formula for filling your cart with high-calorie foods, and likely spending more money than expected.
Now we learn that food shopping when you're sleep deprived may be just as dangerous. This simple experiment looked at what foods 14 normal-weight men bought on 2 morning shopping trips. One trip followed a single night of sleep deprivation. The other came after a good night's sleep.
For each trip, the men received the equivalent of 50 U.S. dollars to spend. They were told to buy as much as they could out of a possible 40 items. Twenty of the foods were high-calorie and 20 were low-calorie.
To make sure the men weren't hungry, they were fed a solid breakfast before food shopping.
The men bought more grams of food and more high-calorie foods on the morning after sleep deprivation than they did after a more standard night’s sleep.
Not getting enough sleep is linked with gaining weight. This study adds another potential reason. Earlier studies have suggested other possible reasons:
- Slower metabolism
- Carbohydrates stored as fat rather than used for energy or burned off as heat
- Cells that don't respond as well to insulin. This means the pancreas makes more insulin. And higher blood insulin levels cause weight gain.
- Lower levels of leptin, a hormone that suppresses appetite, and increased levels of ghrelin, a hormone that stimulates appetite
What Changes Can I Make Now?
Be aware of how your body responds when you don't get enough sleep. If possible, schedule your food shopping on a day after you can get at least 7 hours of sleep. Focus on mindful eating even more than usual when you know you are sleep deprived and tired.
Quality of sleep matters just as much as how long you sleep. This can be a real challenge for people who work the night shift or can't get into bed when it's dark outside.
If you are fortunate enough to have a regular sleep schedule, 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 TV 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 TV. 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. Do the less challenging activities later. This helps you 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. Consume it at least 4 hours before bedtime.
- To decrease urination during the night, don't drink any liquids 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 15 to 20 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.
If you do have an irregular sleep schedule, try to avoid bright lights for at least an hour before you get into bed. Wear sunglasses if necessary.
If you work the night shift, you will need to adjust this advice based on your schedule. For example, go directly to bed as soon as you get home from work.
What Can I Expect Looking to the Future?
This may be a small study, but it is just the type of research we need. Studies like this can help us understand the behaviors that can lead to weight gain and obesity.
It's interesting that the researchers decided to choose men rather than women. Perhaps in Sweden, where the study was done, men do more of the grocery shopping. We certainly need to see if the results will be the same in women.