Turn lights off to lose weight

When Melissa McCarthy (“Bridesmaids,” “Can You Ever Forgive Me?” and the upcoming “Super intelligence ”) decided to do something about her weight — she shed 75 pounds — one of her first steps was to change her sleep habits: “You bring it real down ... and you go to bed at 7:30 — that’s the trick.”

But it turns out there’s more to it than that. Anew observation al study published in JAMA looked at 44,000 women who had no history of cardiovascular disease or cancer, didn’t work off-hour shifts and were not pregnant at the study’s start. What the researchers discovered was that women who reported sleeping in a room with a TV or lights on were heavier than women who did not. Furthermore, over the course of around sixyears, women who slept in even dimly lit rooms gained around 11 pounds more than women who slept in the dark. (The researchers didn’t check, but we’re thinking ... TV? We bet light from computers, tablets and phones might contribute!)

The reason light at night leads to weight gain is that it messes with the ebb and flow of lightsensitive hormones such as melatonin and cortisol. That affects your metabolism in many ways. So to avoid weight gain, upgrade your nutrition, increase physical activity and get that bedroom nice and dark:

— No TV/digital light sources. No light from other rooms or fixtures in the bedroom. (Red wavelength light, however, is OK. It doesn’t affect melatonin levels.)

— Use a padded eye shade. — Install light-blocking shades and curtains to keep light pollution out of the bedroom.

Mehmet Oz, M.D. is host of “The Dr. Oz Show,” and Mike Roizen, M.D. is Chief Wellness Officer and Chair of Wellness Institute at Cleveland Clinic. To live your healthiest, tune into “The Dr. Oz Show” or visit www.sharecare.com.