Pregnant women who had more light exposure three hours before bed were more likely to develop gestational diabetes — ScienceDaily

Pregnant women should dim the lights at home and turn off or at least dim their screens (computer screens and smartphones) a few hours before bed to reduce their risk of gestational diabetes, according to a new Northwestern Medicine study.

Women who developed gestational diabetes in the multisite study had more light exposure in the three hours before bedtime. They did not differ in their exposure to light during the day or in their sleep or activity levels compared to those who did not develop it.

“Our study shows that exposure to light before bedtime may be an under-recognized but easily modifiable risk factor for gestational diabetes,” said lead study author Dr. Minjee Kim, assistant professor of neurology at Northwestern University Feinberg School of Medicine and a Northwestern Medicine neurologist. .

Increasing evidence suggests that exposure to light in the evening before bedtime may be associated with impaired glucose regulation in nonpregnant adults. However, little is known about the effect of evening light exposure during pregnancy on the risk of developing gestational diabetes, a common complication of pregnancy with significant health implications for both mother and offspring.

This is believed to be one of the first multi-site studies to examine exposure to light before bedtime in relation to the risk of developing gestational diabetes.

The study will be published March 10 in the American Journal of Obstetrics and Gynecology Maternal Fetal Medicine.

Rise in gestational diabetes ‘alarming’

Gestational diabetes is on the rise in the US and worldwide. About 4.5% of first-time pregnant women with a baby born between 2011 and 2013 developed gestational diabetes, increasing by an average of 3.4% every three years through 2019. In 2020, the rate of gestational diabetes was 7, 8% of all US births

“It’s worrying,” Kim said. “Gestational diabetes is known to increase obstetric complications and the mother’s risk of diabetes, heart disease and dementia. Offspring are also more likely to have obesity and hypertension as they grow.”

Data show that women who have gestational diabetes are nearly 10 times more likely to develop type 2 diabetes than those who do not have glucose problems during pregnancy, Kim said.

Exposure to bright light before bed can come from bright lights in your home and from devices such as televisions, computers and smartphones.

“We don’t think about the potential harms of keeping the environment bright from the time we wake up until we go to bed,” Kim said. “But it should be dim enough for several hours before we go to bed. We probably don’t need that much light for anything we normally do at night.”

Scientists don’t know which bright light source is causing the problem, but it could all add up, Kim said.

“Try to reduce the light in your environment in those three hours before you go to bed,” Kim said. “It’s best not to use your computer or phone during this time. But if you must, keep the screens as dark as possible,” Kim said, suggesting people use the night light option and turn off the blue light.

If pregnant women develop gestational diabetes in their first pregnancy, they are more likely to develop gestational diabetes in their next pregnancy.

Exposure to light before sleep increases heart rate and can lead to abdominal obesity, insulin resistance, increased blood pressure

Exposure to light before sleep can affect glucose metabolism through sympathetic overactivity, meaning the heart rate rises before sleep when it should be falling. “There seems to be inappropriate activation of the fight-or-flight response when it’s time to rest,” Kim said.

Data show that sympathetic overactivity can lead to cardiometabolic disease, which is a group of conditions including abdominal obesity, insulin resistance, elevated blood pressure, and lipid imbalance, all of which lead to cardiovascular disease.

The study of 741 women in their second trimester was conducted at eight clinical sites in the US between 2011 and 2013. Participants’ light exposure was measured with an actigraph worn on their wrists. The women were measured during the second trimester of pregnancy, at the time when they underwent routine screening for gestational diabetes.

After separately adjusting for age, BMI, race/ethnicity, education, commercial insurance, employment schedule, season, sleep duration, average sleep, sleep regularity index, and light exposure during of the day, bedtime light exposure remained significantly associated with gestational diabetes.

The increasing rate of gestational diabetes has been attributed in part to increasing body mass index and older age of pregnant women.

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

Weight loss and exercise also reduce the risk of gestational diabetes, which is important but takes a little effort.

Dimming the lights is an easy modification

“Dimming the lights is an easy modification you can make,” Kim said.

“Now I’m the light police in the house,” Kim said. “I see all this light that I never thought about before. I try to reduce the light as much as possible. Only for evening activities like dinner and bathing the children, no bright light is needed.”

“This study highlights the importance of reducing light exposure in the hours before sleep,” said senior author Kathryn Reed, Feinberg Research Professor of Neurology.

The name of the paper is “The association between exposure to light before bedtime in pregnancy and the risk of developing gestational diabetes mellitus”.

Other Northwestern authors are Drs. Phyllis Zee, Rosemary Brown, Blas Garcia-Kanga, and Michael Wolff.

The research was supported by grant R01HL105549 from the National Heart, Lung, and Blood Institute of the National Institutes of Health.

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