Published on June 06, 2016

Are you a light sleeper? Stay away from bright lightsAre you a light sleeper? Stay away from bright lights

A streetlight near your house gives you some peace of mind, but you might be wrong if you think it’s helping you sleep better.

“We use outdoor lighting, such as street lights, to be more active at night and to increase our safety and security,” said sleep researcher Maurice Ohayon, MD, PhD, of Stanford University in a press release about a new study. “The concern is that we have reduced our exposure to darkness and it could be affecting our sleep.”

In Dr. Ohayon’s study, presented recently at the American Academy of Neurology’s annual meeting, 15,863 people were interviewed about their sleep habits and their quality of sleep as well as medical and psychiatric disorders. Researchers used satellite data to see how much outdoor light the subjects were exposed to at night. In urban areas, people were exposed to nighttime lights that were as much as six times as intense as the exposure for people in small towns and rural areas.

“The study shows that nighttime light affects sleep duration and was significantly associated with sleep disturbances,” according to the news release. In the areas with more intense light, people were six percent more likely to get less than six hours of sleep per night, and they were almost twice as likely (29 percent vs. 16 percent) to complain about the quality or quantity of their sleep.

If that’s not enough of a nightmare, sleepers in the brightly lit neighborhoods had a higher chance of waking up confused in the middle of the night.

“Light is a very well-known trigger for awakening or keeping a person awake,” said Mir F. Shuttari, MD, a Falmouth pulmonologist who is certified by the American Board of Sleep Medicine.

Dr. Shuttari explained that zeitgebers are external cues, like sunrise and sunset, which help our body stay in synch with the Earth’s 24-hour cycle. They help you wake up and help you fall asleep.

“The system in the brain depends on outside cues and among them is sunlight, in particular, but any bright light can have an effect,” he said. “If you have above a certain intensity of light, it definitely will cause an awakening response.

“There is a very sensitive sensor in our brain, right over the nerves that come to the retina that gives a signal to the brain to wake up. It’s an attempt by our body to keep us in tune with sunlight. That signal will wake up so you can be active and do what you’re supposed to do.”

But too much man-made light can have the same awakening effect, as Dr. Ohayon’s streetlights study showed.

“If it is very low and not terribly bright, like the background around dusk and after a sunset, it shouldn’t have a dramatic effect,” said Dr. Shuttari. “But if it’s bright light, where you can read, that will wake you up and then you need to have a shade on the window. Anything that cuts down the light from entering the windows will be helpful.”

Sleep masks, which cover the eyes, are also helpful, he said. They are available for less than $10 online or at many larger pharmacies.

“They’re very handy,” he said. “If you’re traveling in a plane, especially if you’re crossing time zones, you’ll see a lot of people with them.”