EMBARGOED FOR RELEASE: June 11, 2009, at 12:01 a.m.

Kelly Wagner
(708) 492-0930, ext. 9331
WESTCHESTER, Ill. – Body mass index (BMI) varies as a function of habitual sleep duration, according to a research abstract that will be presented on Thursday, June 11, at SLEEP 2009, the 23rd Annual Meeting of the Associated Professional Sleep Societies.
Results indicate that twins who slept between 7 and 8.9 hours each night had a lower mean BMI (25.0 kg/m2) compared to those who regularly slept either more (25.2 kg/m2) or less (26.4 kg/m2) per night. The relationship between sleep duration and BMI remained significant after controlling for genetics and shared environment.
According to lead author Nathaniel Watson, MD, co-director at the University of Washington Sleep Institute in Seattle, sleep habits have a significant impact on weight and BMI.
“Findings of the study point towards an environmental cause of the relationship between sleep duration and BMI,” said Watson. “Results were robust enough to be present when the sample was limited to identical twins.”
The study involved data from 1,797 twins, including 634 twin pairs (437 monozygotic, 150 dizygotic and 47 indeterminate pairs) and 529 individual twins with a mean age of 36.8 years. Habitual sleep duration was obtained by self-reported length of sleep per night, and BMI was calculated by self-reported height and weight. Of the sample, 68.3 percent was female, and 88.2 percent was Caucasian. Results persisted in a co-twin control analysis of within twin pair differences in sleep duration and BMI.
According to the American Academy of Sleep Medicine, previous studies have also found that adults who have a sleep duration that deviates from the recommended 7 to 8 hours a night are at elevated risk for serious health conditions. More information about the importance of sleep can be found at: http://www.sleepeducation.com/.
SLEEP 2009 will bring together an international body of 6,000 leading researchers and clinicians in the field of sleep medicine to present and discuss new findings and medical developments related to sleep and sleep disorders.
More than 1,300 research abstracts will be presented at SLEEP 2009, a joint venture of the AASM and the Sleep Research Society. The scientific meeting will bring to light new findings that enhance the understanding of the processes of sleep and aid the diagnosis and treatment of sleep disorders such as insomnia, narcolepsy and sleep apnea.
Abstract Title: Does sleep duration influence body mass index in twins?  
Presentation Date: Thursday, June 11
Category: Sleep in Medical Disorders
Abstract ID: 0981