Is your bedroom making you fat?

Is your room too bright at bedtime?

Maybe you fall asleep watching TV—or keep a light on for late night trips to the bathroom. Maybe you just live in a city, where the streetlights and neon signs never turn off.

Whatever the reason, if your sleep isn’t suffering, you may not think those lights are a problem. But if you’re a woman, at least, new research shows that they may actually be affecting your waistline…

Bright lights, big waistline

Researchers collected data from more than 43,000 participants of the Sister Study—a study designed to look for risk factors for cancer and other diseases in women.

All of the subjects were female and between the age of 35 and 74. None of the subjects had histories of cancer or heart disease, and none were pregnant when the study started. In addition, none of them were shift workers or day sleepers.

The scientists measured weight, height, waist and hip circumference, and body mass index (BMI) at baseline and again five years later. This information was then used to evaluate how artificial light exposure at nighttime might influence obesity risk.

And there was an undeniable link—which varied, depending on the level of light exposure.

Small nightlights didn’t have strong links to weight gain. But if women slept with a light or a television on, they were 17 percent more likely to gain ten pounds over the five year period. Outside lights had a more modest effect on weight—but an effect, nevertheless.

And while researchers acknowledged the obvious links between poor sleep and obesity, the connection between nighttime light exposure and weight gain stands on its own.

The findings also didn’t change when researchers accounted for factors like age, sharing a home with a spouse or children, race, socioeconomic status…or even calorie consumption and physical activity levels.

In other words, bright lights at bedtime could be singlehandedly making you fat.

Fight obesity with total blackout

I’ve told you countless times that a TV in your bedroom is a horrible idea. The blue light emitted by electronic devices—phones and tablets included—is particularly problematic.

But this research drives home the fact that any bright light at bedtime could be sabotaging your weight, even if it doesn’t seem to be messing with your sleep.

And why wouldn’t it? Without complete darkness, your pineal gland won’t release enough melatonin. And while this hormone’s main role is to regulate sleep cycles, it also does a whole lot more than that.

In fact, melatonin has a role in preventing everything from cancer and diabetes to migraines and arthritis. So really, the only surprising thing here would be if melatonin disruptions didn’t contribute to obesity.

But judging by this research, at least, it appears that they do. Which means you have a decision to make: Invest in blackout shades and a sleep mask…or put that money toward a new wardrobe of bigger clothes.

As a New Yorker living in the “city that never sleeps,” I know which one I’m choosing. And wherever you live, I urge you to do the same.

P.S. If getting a good night’s sleep seems like an out-of-reach dream, there are many things you can do to make that dream a reality. That’s why I created my Perfect Sleep Protocol. This innovative learning tool is filled with easy, drug-free recommendations to cure your insomnia so you can enjoy perfect sleep for the rest of your life. Click here to learn more, or sign up today.


“Sleeping with artificial light at night associated with weight gain in women.” Science Daily, 06/10/2019. (