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Less Sleep, More Weight
Tuesday, August 22, 2006
Adequate sleep is essential to proper health. Despite the body appearing to be inactive during sleep, this is actually an active time for the brain, and adequate sleep is important alertness and peak mental functioning. Millions of Americans do not get enough sleep. It is estimated that at least 40 million Americans suffer from sleep disorders. The National Sleep Foundation has indicated that 60% of adults report having difficulty sleeping at least a few nights a week. Greater than 40% of adults report daytime sleepiness for a few days each month. It is also estimated that inadequate slumber may contribute to more than 100,000 motor vehicle accidents per year and approximately 1500 deaths each year in the United States.For more information the topic of sleep and the importance of sleep:
Recent investigations are demonstrating an unexpected benefit of sleep: it may help keep off the pounds. In one study which included 68,000 women over a 16 year period, women who slept 5 hours a night were 32% more likely to experience major weight gain than those who slept 8 hours per night. In the Wisconsin Sleep Cohort study, which examined the sleep patterns of over 1,000 volunteers, a correlation was found between sleeping less and gaining weight. In people getting less than 8 hours of shuteye per night (which accounted for approximately 74% of the sample), increased body mass index (a measure of body weight for height) was proportional to diminished sleep. There was approximately a 4% increase in body mass index in those in whom the average nightly sleep duration was 5 hours versus 8 hours.
Two hormones have been implicated in the connection between sleep loss and increased body weight. These hormones are called ghrelin and leptin. Ghrelin is a peptide hormone produced primarily by the stomach. It triggers appetite in humans. It has been found to increase in those not getting enough sleep. Elevated ghrelin levels may be responsible in part for increased sensation of hunger with sleep deprivation. The other hormone, leptin, is produced by fat cells. When leptin levels are low, appetite increases. With inadequate sleep, leptin levels drop. This may also contribute to increased hunger with insufficient shuteye.
In the Wisconsin Sleep Cohort study, the researchers demonstrated a 14.9% increase in ghrelin and a 15.5% decrease in leptin in participants who averaged 5 hours of sleep a night compared with those who slept 8 hours per night. Researchers at the University of Chicago have demonstrated a similar trend. In a study published in the December, 2004 issue of the Annals of Internal Medicine, investigators noted that healthy young males who slept only 4 hours a night had an 18% decrease in leptin levels, as well a 28% increase ghrelin after only 2 nights. The participants reported a 24% increase in appetite with sleep deprivation. In particular, they craved sugary, starchy, and salty foods (such as candy & potato chips) -- the types often associated with "empty calories".
In the Nurses Health study, which followed more than 68,000 for 16 years, women who slept 5 hours a night were 32% more likely to have major weight gain and 15% more likely to become obese compared with females who averaged 7 hours of sleep per night. Major weight gain was defined as an increase of 33 pounds or more over the 16 year period. Females who slept for an average of 6 hours per night were 12% more likely to experience weight gain as compared to those who slept 7 hours per night.
An epidemiological study from Columbia University in New York evaluated government data on over 6,000 people. Investigators found that those getting 5 hours of sleep per night were 50% more likely to be obese than normal sleepers, and individuals getting 6 hours of sleep per night were 23% more likely to be obese. On the other hand, persons getting 10 or more hours of sleep per night were 11% less likely to be obese.
It is estimated that at least 63% of Americans do not get the recommended 8 hours of sleep per night. Currently, the average adult gets slightly less than 7 hours of sleep on weeknights. Since the invention of the light bulb, Americans have averaged one hour less sleep per night. Don't underestimate the value of a good night's sleep!For more about these studies and the link between hunger and sleep deprivation, check out the following news: