Sleep can be a powerful tool for weight loss. Being short on sleep affects the hormones that regulate appetite, stimulating hormones that signal hunger and suppressing those that signal feelings of satiety, or fullness. When we're low on sleep, we burn fewer calories during our waking -- and our sleeping -- hours. Lack of sleep also compromises judgment and willpower, leaving us more vulnerable to making poor food choices and to overeating. Making sleep a priority protects against these weight-gain risks.
A new study suggests that sleep is even more powerful than we knew, and has the capacity to influence weight gain at the genetic level. Researchers from the University of Washington Medicine Sleep Center have discovered that the amount of time we sleep -- our sleep duration -- can affect how active a role our genes play in our weight.
Researchers used pairs of twins, both fraternal and identical, to examine whether sleep could have an effect on the genetic factors that influence weight. Weight is influenced by a number of factors, including environmental circumstances and genetic predisposition. Genetic influences include metabolism, fat-storage patterns, energy expenditure, hunger and satiety.
The study looked at sleep habits, weight, and BMI for 1,088 pairs of twins -- 604 identical, and 484 fraternal. Roughly two-thirds, or 66 percent, of the participants were women, and their average age was 36.6. By studying twins -- and using a particular type of biometric genetic analysis -- researchers were able to interpret how sleep amounts and genetic factors influenced weight and BMI.
What did they find?
- Individuals who slept longer had lower BMI than those who slept less
- Individuals who slept less than seven hours per night had a higher BMI and a greater risk of weight gain as a result of genetic factors
- The average night's sleep was 7.2 hours
Duration of sleep appeared to affect the degree of influence that genetic factors had on weight.
- Genetic factors played a role in 70 percent of weight differences among twin pairs who slept less than seven hours per night
- Among those twins who slept more than nine hours per night, genetic factors were responsible for 34 percent of weight differences
- For those who slept between seven and nine hours per night, genetic factors influenced 60 percent of weight variations among twins
When participants reported sleeping less, genetic influences stepped up to play a much larger role in affecting weight and BMI compared to those who reported sleeping for longer periods. Sleeping for longer duration -- especially for nine or more hours per night -- appeared to diminish the influence of genetic factors on weight.
The relationship between sleep and weight, and the tendency of people short on sleep to gain weight, has been well established. Recently, we've seen studies examining the effect sleep has on weight gain from several angles, including:
Timing of sleep: This study showed that late bedtimes and late mealtimes can cause weight gain.
Duration of sleep: This large-scale study looked at the long-term effects of sleep duration on weight, and discovered that too little sleep and too much sleep can both lead to weight gain. Over a 20-year period, people who slept less than six hours per night or more than eight hours per night gained more weight than those who slept between six and eight hours nightly.
Gender differences: Recent research has looked into the differences in how sleep affects weight gain in men and women. This study found that both men and women's weight were affected by lack of sleep. Women, however, were more likely to see their BMI increase as their sleep decreased.
Studies like these are giving us a more detailed, nuanced picture of how sleep influences our ability to lose weight -- or our tendency to gain it. This latest study may be the first to show how sleep can either promote or suppress weight gain by affecting the genetic factors that play a role in weight. There's a lot more to be learned here, including what specific genetic factors are most affected by sleep. But this research could have real implications for treatment of obesity and other weight-related health problems.
We've recently heard some pretty dire forecasts about the epidemic levels of obesity in the United States. A study at Duke University predicts that by 2030, 42 percent of Americans will be obese. That's a significant rise from today's already high level of just over 33 percent. The study also forecasts that the number of Americans who are severely obese -- more than 100 pounds overweight -- will double between now and 2030, rising to 11 percent of the population.
With numbers like these, and the serious -- and seriously expensive -- health risks posed by obesity, we can't afford not to look at every avenue of treatment. Diet and exercise are critical to weight management.
So, too, is sleep.
Michael J. Breus, PhD
The Sleep Doctor™
Everything you do, you do better with a good night's sleep™
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