May 1, 2008 -- The number on your bathroom scale may have a lot to do with how much shut-eye you get each night.
A new study in the journal Sleep upholds the widely accepted notion that body weight plays a large role in how well a person sleeps. Francesco P. Cappuccio, MD, of Warwick Medical School in England, and colleagues reviewed worldwide literature regarding obesity and short sleep duration in children and adults to determine if existing evidence supported a link between short sleepers and obesity.
The researchers' analysis showed a "striking, consistent" pattern of increased odds of being a short sleeper if you are obese regardless of age. According to the American Academy of Sleep Medicine, you are a short sleeper if you regularly sleep fewer hours than the average member of your age group. For this analysis, short sleep was defined as five hours or less for adults and less than 10 hours for children.
"The 60% to 80% increase in the odds of being a short sleeper amongst obese was seen in both children and adults," the researchers write in the journal article.
The study review included 634, 511 males and females ages 2 to 102 identified from studies around the world.
"This study is important as it confirms that this association is strong and might be of public health relevance. However, it also raises the unanswered question of whether this is a cause-effect association. Only prospective longitudinal studies will be able to address the outstanding question," Cappuccio says in a news release.
Though Cappuccio's team did not investigate the reasons for the connection between shortened sleep time and obesity, the study data involving the adults revealed a significant negative link between hours of sleep and body mass index (BMI). According to the researchers, some have suggested that short sleep may prompt hormonal changes that fuel appetite and caloric intake, leading to obesity.
In the past 30 years, the number of overweight children has more than doubled, according to the National Heart, Lung and Blood Institute. Approximately 61% of U.S. adults aged 20-74 are either overweight or obese. Carrying extra weight increases your risk for heart disease, diabetes, and obstructive sleep apnea, a sleep-related breathing disorder that causes your body to stop breathing during sleep.
Experts recommend 7-8 hours of sleep a night for adults. Recommendations for children vary with age, but in general, they need more than adults do.
Establishing a consistent and relaxing bedtime routine, avoiding caffeine, chocolate, and other stimulants, and removing TVs and computers from the bedroom are some tried-and-true ways of improving sleep. Keeping the room cool and dark and getting up the same time every day may also lead to better sleeping habits.
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