ABC News - Despite what past research has shown, getting more sleep may not be all bad for the waistline.
A new study found that getting more than nine hours of sleep a night could turn off some of the genetic activity linked to body weight.
That's because, according to researchers, environmental factors such as diet and exercise play a bigger role in determining weight with longer sleep durations.
"In theory, you have control over environmental factors, so the choices you make may have a bigger impact on your weight the longer you sleep," said Dr. Nathaniel Watson, co-director of the UW Medicine Sleep Center in Seattle.
Watson and colleagues analyzed self-reported data on height, weight and sleep from more than 1,000 pairs of Caucasian twins from the University of Washington Twin Registry.
The study also showed that too little sleep is also detrimental, since genetic factors are more influential when people are sleep-deprived. Those genetic pathways, Watson said, are not yet known.
Taken together, their findings suggest that sleeping too much and sleeping too little can adversely affect body weight, and although it's generally accepted that getting too much sleep can contribute to obesity, it may not play as big a role as originally thought.