[Bonnie]

I am a real night owl, but I've been reading lots of sleep research articles lately that are making me change my tune. Here's one. Trust me, this kind of study is the only kind that will get me into bed on time!

Hum... now it is requiring registration to read the article. Here are some snippets:

Short or Long Sleep Duration Linked to Weight Gain

April 7, 2008 — Patients who slept for short or long durations experienced an increase in weight compared with those who slept for an average duration of 7 to 9 hours, according to the results of a longitudinal study reported in the April issue of Sleep.

"Individual and environmental factors that have an influence on energy balance are not fully understood," write Jean-Philippe Chaput, MSc, from Laval University in Quebec City, Quebec, Canada, and colleagues. "Current treatments for obesity have been largely unsuccessful in maintaining long-term weight loss, suggesting the need for new insight into the mechanisms that result in altered metabolism and behavior and may lead to obesity."

....
The investigators compared changes in adiposity indices among groups determined by sleep duration: short (5 - 6 hours), average (7 - 8 hours), and long (9 - 10 hours).

Compared with average-duration sleepers, short-duration sleepers gained 1.98 kg more in a 6-year period (95% confidence interval [CI], 1.16 - 2.82), and long-duration sleepers gained 1.58 kg more (95% CI, 1.02 - 2.56) after adjustment for age, sex, and baseline BMI. At 6 years, short-duration and long-duration sleepers were 35% and 25% more likely to experience a 5-kg weight gain, respectively, vs average-duration sleepers.

Compared with average-duration sleepers, short-duration sleepers had a 27% increased risk for the development of obesity, and long-duration sleepers had a 21% increase in risk. Adjustment for energy intake and physical activity participation did not affect these associations, which remained significant after inclusion of important covariates.