Two studies published in the past week link our sleep patterns to weight gain, and one of them also links too little or too much sleep to an increase in smoking and alcohol use.
According to the survey of 87,000 U.S. adults released yesterday by the U.S. Centers for Disease Control and Prevention (CDC), people who sleep less than six hours a night were shown to be more likely to be obese, have higher smoking and alcohol rates, and are less likely to engage in physical activity than those receiving 7 to 9 hours of sleep. People who sleep more than nine hours are also more likely to be obese.
According to another study published on May 1 that examined the research literature on the link between sleep and obesity, researchers found a consistent pattern of increased odds of being a short sleeper if you are obese, both in childhood and adulthood.
The research adds weight to a stream of studies that have found obesity and other health problems in those who don’t get proper shuteye, said Dr. Ron Kramer, a Colorado physician and a spokesman for the American Academy of Sleep Medicine.
“The data is all coming together that short sleepers and long sleepers don’t do so well,” Kramer said.
No cause and effect relationship can be shown by either study — it’s not clear whether those who sleep poorly are more likely to gain weight, or if obesity causes one to get less sleep. The study also did not account for the influence of other factors, such as a mental health concern such as depression, which can contribute to heavy eating, smoking, sleeplessness and other problems.
CDC Study Results
Obesity was seen amongst 33 percent of those who got less than 6 hours of sleep and 26 percent of those who slept longer than 9 hours. Obesity was a concern for only 22 percent of those who received 7 to 8 hours of sleep.
Smoking was highest for people who got under six hours of sleep, with 31 percent saying they were current smokers (as opposed to the national average of 21 percent). People who received 7 to 8 hours of sleep per night smoked less, 18 percent, according to the survey data.
For alcohol use, those who slept the least were the biggest drinkers. However, alcohol use for those who slept seven to eight hours and those who slept nine hours or more was similar.
In another measure, nearly half of those who slept nine hours or more each night were physically inactive in their leisure time, which was worse even than the lightest sleepers and the proper sleepers. Many of those who sleep nine hours or more may have serious health problems that make exercise difficult.
Sleep journal Study Results
Francesco P. Cappuccio, MD, of Warwick Medical School in the United Kingdom, and colleagues performed a systematic search of publications on the relationship between short sleep duration and obesity risk. The study appeared in the May 1 issue of the journal Sleep.
For the children, 13 population samples from the 12 studies were included in the pool analysis, for a total of 30,002 participants from around the world. The subjects’ age ranged from two to 20 years. Seven of 11 studies reported a significant association between short sleep duration and obesity.
For the adults, 22 population samples from the 17 studies were included in the pool analysis, for a total of 604,509 worldwide participants. The subjects’ age ranged from 15-102 years. Seventeen population samples showed a significant association between short duration of sleep and obesity. Unlike studies in children, all studies in adults showed a consistent and significant negative association between hours of sleep and BMI.
“By appraising the world literature, we were able to show some heterogeneity amongst studies in the world,” said Cappuccio. “However, there is a striking consistent overall association, in that both obese children and adults had a significantly increased risk of being short sleepers compared to normal weight individuals.”
“This study is important as it confirms that this association is strong and might be of public health relevance,” he continued.
“However, it also raises the unanswered question yet of whether this is a cause-effect association. Only prospective longitudinal studies will be able to address the outstanding question.”
While an increasing number of adults are considered overweight, the number of overweight children is also on the rise. According to the National Heart, Lung and Blood Institute, the percentage of overweight children and teens has more than doubled in the past 30 years. Today, about 17 percent of American children aged two to 19 are overweight. An estimated 61 percent of U.S. adults aged 20-74 years are either overweight or obese. About 34 percent of these people are overweight and 27 percent or 50 million people are obese.
While eating healthy and exercising regularly are important precautions to take to reduce one’s chances of being overweight, getting enough sleep is equally as important.
A lack of sleep can lead to increased stress, relationship and work issues, and put one’s general physical health at increased risk.
Sources: National Center for Health Statistics, part of the Centers for Disease Control and Prevention, and the journal Sleep