A well-lit room is a beautiful thing…except when it’s time to get some sleep. A new study shows that too much light at night can negatively affect a person’s immunity and endocrine systems, as well as other health issues.
Scientists often recommend sleeping in complete darkness to better enhance the quality of sleep. Staying true to the circadian rhythms that are innate within the body is also known to treat insomnia and other sleep problems, showing the importance of light during the day and darkness during the night.
Now, a study from Ohio State University shows that exposure to light at night, in addition to promoting sleeplessness, can disrupt the naturally occurring systems in the body, including immune and endocrine function.
To examine the effects of light exposure on sleep quality and overall health, the team of researchers used nocturnal hamsters as their subjects. The hamsters were split into two groups. One group experienced days and nights as usual, while the other group was exposed to dim light during their sleep time.
Right off the bat, the researchers noticed weight gain in all of the hamsters exposed to light pollution. The hamsters were then allowed to mate, and the researchers raised the hamster pups in normal conditions (light days, dark nights). What they found was that the second generation of hamsters had impaired immune function and decreased endocrine activity when compared to the second generation of hamsters kept in normal conditions.
This exposes a hereditary response to light pollution, and the effect it can have on subsequent generations.
“Now, we’re seeing for the first time in these hamsters that it’s possible this damage isn’t just being done to the affected individuals, but to their offspring as well. These weren’t problems that developed in utero. They came from the sperm and the egg,” said Randy Nelson, Ph.D., professor and Chair of Neuroscience at Ohio State’s Wexner Medical Center. He commented on the surprising effect that the fathers had on the children as well, as epigenetic effects are usually passed down from the mother. However, the effect of light pollution was passed down from the father as well.
The DNA of the hamsters was unchanged in the second generation. However, the scientists believe that the epigenetic expression of the hamsters’ DNA was altered, therefore passing down the negative effects of light at night. Additionally, this study ties into other research, which has shown that light pollution at night can be linked to certain cancers and other fatal medical conditions.
Nelson commented, “I think people are beginning to accept that light pollution is serious pollution and it has health consequences that are pretty pronounced — an increase in cancers, depression, cardiovascular disease, diabetes and anxiety disorders. We should be concerned about the increasing exposures to light at night from our tablets and phones and TVs.”