Sleep disturbances have adverse cardiovascular consequences and are linked to glucose intolerance and obesity.
Weight loss and exercise are primary treatments for obese patients with glucose intolerance yet few lifestyle intervention trials have evaluated changes in sleep quality in relation to changes in body composition and fitness.
New study shows shedding pounds, especially in belly, improves sleep quality
Weight loss, whether it's from dietary changes alone or from diet combined with exercise, can help improve the quality of sleep among people who are overweight or obese, according to a new study by Johns Hopkins researchers.
"We found that improvement in sleep quality was significantly associated with overall weight loss, especially belly fat," says Kerry Stewart, professor of medicine at the Johns Hopkins University School of Medicine and director of clinical and research exercise physiology.
For the six-month study, researchers enrolled 77 people who had type 2 diabetes or pre-diabetes. The participants, all of whom also were overweight or obese, were randomly assigned to one of two groups. One group went on a weight-loss diet and had supervised exercise training, while the other group only had the diet intervention. A total of 55 participants completed all phases of the study.
The participants filled out a sleep survey at the beginning and end of the study to identify sleep problems, including sleep apnea, daytime fatigue, insomnia, restless sleep, excessive sleep or sleepiness, and use of sedatives to aid sleep. Their body mass index and amount of abdominal fat were also measured at the start and end of the study.
Both groups—those assigned to a weight loss diet plus supervised exercise and those who only went on a diet—lost about 15 pounds, on average. They also lost about the same amount of belly fat, about 15 percent, which was assessed by magnetic resonance imaging (MRI).
Although a variety of sleep problems were reported by the participants, none stood out as being the most common, so the researchers analyzed a composite score, which reflects overall sleep health. They found that both groups improved their overall sleep score by about 20 percent with no differences between the groups.
Key Ingredient for Improved Sleep Quality
"The key ingredient for improved sleep quality from our study was a reduction in overall body fat, and, in particular belly fat, which was true no matter the age or gender of the participants or whether the weight loss came from diet alone or diet plus exercise," Stewart says.
Good sleep quality is important in general for good physical and mental health, as well as for a healthy cardiovascular system, notes Stewart. Depending on the cause, chronic sleep disruptions increase the risk of high blood pressure, heart attack, stroke, and irregular heartbeats.
The above story is based on the November 6, 2012 news release by Johns Hopkins Medicine.
The research entitled "Predictors of Sleep QualityImprovement Among Overweight or Obese Individuals: A Randomized ControlledTrial." was presented at the American Heart Association Scientific Sessions on the same day by lead author Soohyun Nam.