Pregnant women can reduce gestational diabetes risk by cutting out screen time at night

CHICAGO — Cases of gestational diabetes are quickly rising, posing significant health risks to both the mother and child. While we may commonly equate diabetes with food and diet, new research from Northwestern University finds that pregnant women who had greater light exposure three hours before sleep were more likely to develop the condition.

As of 2020, gestational diabetes affects almost 8% of U.S. births. Current data also shows that women with the condition are almost 10x more likely to go on to develop Type 2 diabetes compared to those that don’t have glucose intolerance during pregnancy.

“It’s alarming,” says lead study author Dr. Minjee Kim, assistant professor of neurology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine neurologist, in a statement. “Gestational diabetes is known to increase obstetric complications, and the mother’s risk of diabetes, heart disease and dementia. The offspring also are more likely to have obesity and hypertension as they grow up.”

Dimming bright lights around the house can certainly help, but researchers point to additional risks from devices like TVs, computers and phones. While scientists can’t quite pinpoint which exact light sources is implicated most, Kim thinks they might all have a role to play.

Pregnant woman with hands on belly
(Photo by Suhyeon Choi on Unsplash)

“We don’t think about the potential harm of keeping the environment bright from the moment we wake up until we go to bed,” Kim notes, advising women turn on night mode as well as turning off blue light on their devices. “But it should be pretty dim for several hours before we go to bed. We probably don’t need that much light for whatever we do routinely in the evening. Try to reduce whatever light is in your environment in those three hours before you go to bed. It’s best not to use your computer or phone during this period. But if you have to use them, keep the screens as dim as possible.”

The problem with pre-sleep bright light is that it can put the sympathetic nervous system in overdrive, putting the body in “flight or fight” mode. When this happens, the body is inappropriately stimulated, making heart rate rise and negatively impacting glucose metabolism. Existing data shows that overactivity of the sympathetic system can lead to a plethora of conditions like obesity, insulin resistance, high blood pressure and an lipid imbalance, which are all heavily implicated in heart disease.

To learn more, the team studied 741 women in their second trimester (when women are screened for gestational diabetes) across eight clinical U.S. sites between 2011 and 2013. They measured light exposure using an actigraph worn on their wrists, which measures sleep-wake cycles. After adjusting for several possibly interfering variables, pre-sleep light exposure was still significantly linked with gestational diabetes. So while more commonly-discussed risk factors such as weight play a role, there’s more to the story.

“But even after adjusting for BMI and age, gestational diabetes is still rising,” Kim says. “We have a lot to prove, but my personal worry is that light may be silently contributing to this problem without most people realizing the potential harm.”

“This study highlights the importance of reducing light exposure in the hours before bedtime” concludes senior author Kathryn Reid, research professor of neurology at Feinberg.

The findings are published in the American Journal of Obstetrics & Gynecology MFM