Flip the light switch in your bedroom and a mini-constellation of twinkling lights appears, from the digital alarm clock to the DVD player to the sparkling blue Internet router. Groups like the International Dark Sky Associ-ation have done an excellent job of raising awareness about the need to preserve our starry skies. Ecologists have documented many negative impacts of too much light at night on wildlife—birds forget to migrate; Florida turtles mistake streetlights for the moon. As it turns out, the perpetual lightbulb is not so great for human health, either.
Sleep researchers learned years ago that the hormone melatonin has a lot of power over how we sleep. If levels dip too low, our sleep/wake cycle gets out of wack. And the best way to build up melatonin levels, it turns out, is to get enough sleep. But here’s the other key: You have to sleep in darkness, a difficult feat in the era of blinking electronics. So, what’s at stake? Scientists explain that at the most basic level, if you don’t get enough quality sleep, your odds of being in an accident go up—and your productivity goes down. Poor sleep has an impact on obesity, high blood pressure and other health conditions. And mental health issues such as bipolar disorder and Seasonal Affective Disorder are related to an inconsistent sleep/wake cycle.
Growing evidence also points to a possible connection between light at night, melatonin levels and an increased risk for breast cancer. University of Connecticut cancer epidemiologist Richard Stevens, Ph.D., was one of the pioneer researchers in this area. It is still unclear how much light, and what type of light exposure, might contribute to this breast cancer risk. Studies have shown, for example, that night-shift workers who disrupt their circadian rhythms have higher rates of breast cancer. “I”m not sure there would be a consensus that light at night causes breast cancer,” Stevens says. “There is mounting evidence, but it’s not proven yet.”
Since so much is still unknown in this field, no one is quite sure if the typical array of electronics in an American home would be enough to trigger this risk. But Stevens suggests, based on his studies, that it can’t hurt to simply pull the plug and sleep in the dark—just in case.
“We began our evolutionary path three billion years ago with 12 hours of dark and 12 hours of sun,” Stevens says. “Now we don’t get enough of either one—this is a huge change in our human environment.” Stevens is also concerned about the growing number of people who regularly pop sleeping pills like Ambien or Lunesta. There are better ways to deal with insomnia, he says.
One may be a different perspective of what constitutes a full night’s sleep. New research by National Institutes of Health scientist Dr. Walter Brown shows that humans may naturally sleep in shifts. If you go to sleep at 11 p.m., then wake briefly at 2:30 a.m. every night, that may actually be normal and nothing to worry about. Brown refers to a document by Roger Ekrich, professor of history at Virginia Polytechnic Institute, who found evidence that during pre-industrial times, people regularly woke in the early morning hours to meditate or do household chores by candlelight, then went back for the “second sleep” shift.
So much of sleep has to do with your attitude toward sleeplessness, Stevens says. If you don’t make a big deal of it—and as long as you stay in the darkness—you can often fall back asleep.
Meanwhile, scientists are learning more about how different types and frequencies of light affect our biorhythms. In one study, Mariana Figueiro, Ph.D., of the Lighting Research Center at Rensselaer Polytechnic Institute (RPI) helped a group of elderly nursing-home patients improve their sleep by adjusting the lights in their living quarters. The study showed the patients were not sleeping well because nurses kept a fluorescent light on above their beds. The RPI team switched to amber LED lights that were hooked up to a motion sensor. During the day, the patients were exposed to blue LED light, which appears to energize people much like sunshine and blue skies.
NASA sleep researcher George Brainard also used blue LED lights to help keep astronauts awake and generate a healthy sleep/wake cycle in space. However, those stimulating blue LED lights are not something you want in your bedroom at night. “I firmly believe it’s best to have a bedroom as dark as possible,” Stevens says.
That goes for kids, too, says Chicago sleep expert Dr. Marc Weissbluth, author of Healthy Sleep Habits, Happy Child (Ballantine Books). He suggests keeping lighted clocks and toys, along with illuminated aquariums, out of a child’s room because they are too stimulating at night. “Most children sleep well in pitch-black rooms,” Weissbluth says. “Babies certainly don’t know the difference.”
For toddlers and older kids with night fears, Weissbluth thinks a dim night-light won’t do any harm. But he suggests weaning the child off the habit by gradually adding a dimmer and dimmer light source. Denver Children’s Hospital sleep specialist Dr. Keith Cavanaugh says being in dim light right before bed helps children and adults prepare their bodies for sleep. “I especially worry about teens who spend a lot of time looking at a bright computer screen before bed,” he says.
For adults, sleep experts offer the following tips:
“Try to take a walk or sit out in the sunshine every day.”
“Instead of a digital alarm that glows all night, try one with a little bar you can press when you want to see what time it is.”
“Move electronics to another room, or cover them at night.”
“If you wake in the middle of the night, stay in the dark if possible and do something meditative or relaxing until sleep returns.”