Artificial light might affect weight
Wednesday, October 9, 2019
Dear readers: I heard from many of you last week in response to the headlines that “there was no need to cut down on red and processed meat.” We just were able to get copies of the original studies — five systematic reviews — and several medical students, colleagues and I are plowing through them. Stay tuned and we will soon answer your question “who do I believe?”
Q I heard a news story that sleeping with the TV on will make me gain weight. Is that true? — MG. Winterville
A I saw that story too and was surprised. I have asked Hannah Stiles, a senior East Carolina University dietetic student, to give you more information about the study that made headlines. Here is what she wants you to know.
Did you know that North Carolina has the 19th highest obesity rate in the nation? Just in Pitt county there are about 178,000 residents and almost 3 out of 4 are overweight or obese.
Obesity is such a complicated disease, and so many people struggle with the many factors that play into it. For years we have known that bad sleeping patterns may increase the risk of obesity. Sleeping too little (less than seven hours a night) or too much (more than nine hours) may increase the risk of obesity.
However, being exposed to artificial light while sleeping was proposed as another risk factor by researchers who tracked about 43,700 women for nearly six years in a study that was done on artificial light at night and the obesity risk in women.
The women who were 35 to 74 years old had no history of cancer or heart disease. The women also weren’t shift workers, daytime sleepers or pregnant. For this study, artificial light referred to any light that is not natural. The women talked about having the light from an alarm clock or radio, a television on when sleeping, a light in the room, light from other rooms in the house, a night light, and light coming in through the windows, such as car headlights, street lights, or even porch lights.
They also included the light from using a smart device. The researchers found that having any exposure at all to artificial light at night while sleeping was related to a higher risk of prevalence obesity and incident obesity.
Prevalence obesity refers to the total number of individuals in a population who have this health condition. Incident obesity refers to the number of individuals who develop this specific health condition during a particular time period.
The results from the study propose that exposure to artificial light at night while sleeping may be a risk factor for weight gain and the development of obesity. One of the headlines we heard said “Is something you’re doing at bedtime making you gain weight? Gained 11 pounds.” That could be an increase in body mass index (BMI) of 10 percent or more. For example, a woman with a BMI of 30 might go to a BMI of 33.
The researchers offered several explanations for their results. The artificial light in the room could decrease your quality of sleep. This could then affect your diet and your physical activity you do each day.
Many people who don’t sleep well snack excessively throughout the day. Researchers reported the women who have artificial light in their room during the night were a lot less likely to wake up refreshed. They also take a much longer time falling asleep at night, have difficulty waking up in the morning, are more prone to taking naps, and tend to wake up a few times throughout the night.
Although we are not certain, there have been previous findings (including evidence from animal studies) that prove that artificial light at night could directly suppress the production of melatonin (a hormone secreted by the pineal gland to help regulate sleep), causing a disruption in sleep.
The researchers suggested that the light might also directly affect metabolism by slowing it down. When your metabolism slows down, your body burns fewer calories than it usually would when it is at rest and during activity.
This study is far from proving that watching TV or using your smart device while trying to fall asleep causes weight gain. The researchers themselves said they couldn’t untangle all the factors at play — women who were heavier at the outset, for instance, were already more likely to get less sleep, take longer to fall asleep and not fall a sleeping routine.
To prevent obesity, the strategies known to work including increasing physical activity and eating a healthy diet. But if you have trouble sleeping, lowering your exposure of artificial light at night might help. Try it and see if it helps you.
Professor emeritus Kathy Kolasa, a registered dietitian nutrtionist and Ph.D., is an affiliate professor in the Brody School of Medicine at East Carolina University. Contact her at firstname.lastname@example.org.