WEDNESDAY, June 13 (HealthDay News) -- Obesity has been linked to a host of health problems including heart disease, diabetes and certain cancers, and now new research adds excessive daytime sleepiness to this list.
Well-publicized risks associated with excessive daytime sleepiness among adults include accidents caused by drowsy driving and workplace injuries.
The new, related studies found that the main drivers of daytime sleepiness are obesity and depression. The findings are scheduled to be presented Wednesday at the Associated Professional Sleep Societies annual meeting, in Boston.
"The 'epidemic' of sleepiness parallels an 'epidemic' of obesity and psychosocial stress," study author Dr. Alexandros Vgontzas, of Penn State Hershey Sleep Research & Treatment Center, said in a meeting news release. "Weight loss, depression and sleep disorders should be our priorities in terms of preventing the medical complications and public safety hazards associated with this excessive sleepiness."
Two studies included the same group of 1,741 adults. Of these, 1,173 did not have excessive daytime sleepiness when the study began and 222 did. Depression and obesity were the main risk factors for "new-onset" excessive sleepiness after 7.5 years of follow-up. Weight gain was the top predictor for persistent daytime sleepiness during the same time frame. The rate of new-onset excessive sleepiness was 8 percent, and the rate of persistent daytime sleepiness was 38 percent When sleepy individuals lost weight, they were less tired during the day.
The findings in the first two studies were backed by a study of 103 healthy volunteers, which took place over four nights in a sleep laboratory. It also pointed to obesity and depression as risks for sleepiness, the researchers report.
Dr. Scott Kahan, director of the National Center for Weight and Wellness in Washington, D.C., said that the link between obesity and sleep is a complex one. "This study adds further weight to the fact that it is likely bi-directional." This means that obesity could be the chicken or the egg. "Obesity and weight gain affect sleep, and poor sleep affects weight from a physiological and behavioral perspective," he said. For example, "when you are exhausted, it's hard to care about whether you eat a carrot or a Ho Ho," he said.
People who are overweight or obese are also at higher risk for sleep apnea, a condition marked by pauses in breathing during sleep. This can result in excessive daytime sleepiness. But there is more to the connection between sleepiness and obesity than sleep apnea alone, said Dr. Michael Breus, a sleep expert based in Norfolk, Va. "There are more sleepy people in the world than cases of sleep apnea," he noted.
"We have to slim down as a nation," he said. "One of the effects will be a relief of excessive daytime tiredness and a mild decrease in depression." Sleep problems and depression are also inextricably linked, he said: "When we put people with depression and insomnia on an antidepressant, the insomnia gets better as does their depression, and then you are not as sleepy during the day."
Dr. David Kuhlmann, medical director of sleep medicine at Bothwell Regional Health Center in Sedalia, Mo., agreed. "Weight loss should improve the level of daytime sleepiness and this study would support that," he said.
Because this research was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
What is excessive daytime sleepiness? Find out at the National Sleep Foundation.