Washington, Dec 17 : A new study has revealed that short sleep times in patients with chronic medical diagnoses increases the risk of obesity.

Researchers surveyed 200 patients attending internal medicine clinics to determine their sleep habits, lifestyle characteristics, and medical diagnoses.

It was found that people with a sleep time of less than seven hours had a significantly increased possibility of obesity defined by a body mass index greater than 30 kg/meters2 when compared to the reference group of eight to nine hours.

There was a U-shaped relationship between obesity and sleep time in women suggesting that women who had both short and long sleep times were more likely to be obese.

However, this relationship was not present in men. Other factors predicting obesity in these clinic patients included young age (18 to 49 years), not smoking, drinking alcohol, hypertension, diabetes, and sleep apnea.

Kenneth Nugent, MD, of Texas Tech University and lead author of the study said short sleep times have an association with obesity in adults with chronic medical problems.

“Our study demonstrates that short sleep times have an association with obesity in adults with chronic medical problems and that chronic disease and attendant therapies and/or changes in physical activities do not obscure this relationship, ” Nugent said.

“This study suggests that adults should sleep eight to nine hours per night to maintain optimal weight. Whether or not manipulating sleep time in adults will prevent additional weight gain or facilitate weight loss is unclear. This question will require therapeutic trials in which sleep hygiene is addressed during weight loss studies, ” Nugent added.

A strong link exists between weight and obstructive sleep apnea (OSA), in that your neck gets thicker as you gain weight. This increases the level of fat in the back of the throat, narrowing the airway. With more fat in the throat, your airway is more likely to be blocked.

People with OSA are often obese and have a neck size of more than 17 inches. Many people with OSA also have high blood pressure.

The study is published in the December 15 issue of the Journal of Clinical Sleep Medicine (JCSM).