Connections between sleep habits and body fat highlighted in new research.
Every wish staying slim was as easy as sleeping? According to the authors of one recent study, when and how we rest may in fact play a role in weight and obesity.
Study Links BMI & Sleep Schedules
Sleep and obesity are two important areas of research, as many areas of the world have both high rates of people not getting adequate sleep and growing rates of obesity. One team of researchers at sought to determine if sleep habits might affect weight, finding some interesting links that may be important for future research and public health.
Published November 2013 in the American Journal of Health Promotion, the study is titled “Objectively Measured Sleep Patterns in Young Adult Women and the Relationship to Adiposity.” The study involved 330 college women from two U.S. universities who ranged in age between 17 and 26 years old. Participants wore actigraph monitors for seven days to objectively track sleep and daytime activity. This is different than many other studies, which often rely on non-objective measures like self-report and survey recall. Body fat compositions were assessed before and after the study using body composition machine. Data from the study was assessed statistically and yielded several interesting links between certain sleep habits and body fat.
How Sleep May Affect Weight
After following the women for a week, researchers assessed activity levels, sleep amounts, and sleep schedules, contrasting these with weight and Body Mass Index measures. Here are few highlights from their research:
- Women who slept between 8 and 8.5 hours per night had the lowest body fat levels.
- Sleeping less than 6.5 hours OR more than 8.5 hours was associated with higher levels of body fat in young women.
- Women whose sleep or wake times varied by more than 90 minutes had higher body fat than women who varied by 60 minutes or less.
- Inconsistent wake times were more closely associated with higher body fat than inconsistent bed times.
- Women who experienced higher sleep quality also had lower body fat than women who slept poorly.
Essentially, researchers found that both women who got poor quality sleep, too much or too little sleep, and those who had inconsistent schedules were considerably more likely to have higher body fat than women who kept regular sleep schedules and who got higher quality sleep.
Sleep has been linked to dieting success and failure in other studies as well, with results published in the journal Obesity showing that weight loss improved 33% for 35-55 year old women who experienced quality sleep while dieting. Sleep duration affects a variety of factors that can influence weight loss. These include production of hormones such as leptin, which helps protect the body from overeating by telling us that we are full, and ghrelin which impacts cravings. A sluggish metabolism often occurs after sleep loss which can reduce activity levels.
Tips for Getting Better Sleep
Whether you are in shape or working to lose weight, getting good, quality rest is important for physical and mental health. The science of quality shut-eye is called sleep hygiene, and the following tips and practices are those that have been found to be most important for getting an adequate quantity and quality of rest.
- Set a consistent sleep time and wake times that allow you to get 7-9 hours every night. While many of us had set bedtimes as kids, science is showing that consistent schedules can also benefit adults. In addition to ensuring you get enough time for sleep every day, this practice can also reduce your risk of some sleep disorders, and as illustrated in the study above, setting a sleep schedule may help you maintain a healthier weight as well.
- While it may not sound terribly exciting, maintaining the same sleep schedule on weekends offers the greatest benefit. The Brigham Young study showed that varying one’s schedule by more than 60 minutes affected body fat, but researchers have also found that it can disrupt the natural circadian cycle, making it hard to function on the dreaded Mondays.
- Avoid heavy meals and fatty foods in the evening, and cut out caffeine and other stimulants several hours before bed. Learn more about how diet can help or hurt sleep in our previous article.
- Make sure your bedroom is sleep friendly by keeping electronics and other distractions out. Your room should be very dark and cool. Sounds can be mitigated with ear plugs or white noise machines, while lights can be reduced with window shades or eye masks.
- Make sure your mattress is in good condition so that you can sleep comfortably. If your bed isn’t providing enough support or causes pressure points, it may be time to replace it. If neck pain keeps you up, it may be time for a new pillow. Also, don’t forget to wash sheets and bedding often to limit allergens and other nasties.
- Start a pre-sleep routine so your body and mind are prepared for bed. Some popular ideas include reading a book, taking a bath, doing some light yoga, or simply listening to relaxing music. Physically and mentally stressful activities should be avoided.
- Read more tips on Harvard’s healthy sleep website.
While research is not yet definitive on why exactly sleep affects weight or how, if you are trying to get in shape it may be worthwhile to consider improving sleep habits. Poor sleep quality is also linked with a host of other physical and mental health issues, so developing healthy sleep hygiene is a win-win situation for both your well-being and possibly your waistline.