You’ve dimmed the lights, turned off the TV, shut down your tablet and phone, and you’re ready for a good night’s sleep. But light sneaking into your bedroom from the street still can interfere with your slumber.

 A new study, the first of its kind, squarely documents the effects of external nighttime “radiance” near homes on sleep quantity…and quality. Spoiler alert: It’s not good, and it’s about to get a whole lot worse. New super-bright light-emitting diode (LED) street lamps, already ubiquitous in Los Angeles, are being installed in San Francisco, San Diego, Seattle, Chicago, New York City…and many other communities throughout the country. Compared with standard incandescent street lamps, they use much less energy, which is good for the environment and saves money…but they often emit a lot more light, especially the blue light that interferes with natural melatonin production and good sleep.

That could make our already sleep-deprived nation groggier…and more prone to chronic diseases. Here’s how to protect yourself if you’re living with street glare…and what to do if your town is even considering LED streetlights.


Over an eight-year period, researchers at Stanford University conducted extensive interviews with nearly 16,000 men and women across the US. They asked them about sleep—as well as eating and stress, which can interfere with sleep.

Then they mapped their findings against precise geographic satellite data that pinpointed exposure to the intensity of nighttime light near participants’ homes. Results: Compared with people with less external light at night, those with the most slept about 10 minutes less a night, but more striking was the effect on the quality of their sleep.

  • They went to sleep later and woke up later, a less healthy pattern than earlier retiring/rising.
  • They were more tired during the day.
  • They were more likely to be unhappy with the quality of their sleep.
  • They were more irritable and less functional during the day.
  • The percentage of people who reported excessive daytime sleepiness and impaired daytime functioning, for example, was 2% in the darker areas—and 6% in the brighter ones.

How nighttime light interferes with sleep is well-known. It stops the pineal gland from releasing the hormone melatonin, and that wreaks havoc on your internal clock. “Blue” light, which is emitted from TV screens and especially computers, laptops and phones, is especially bad for melatonin production. That’s the reason sleep experts advise us to turn off our screens 30 minutes to an hour before hitting the sack.

But that’s no help if a street lamp is shining its radiance into your window. Unfortunately, the new LED lights are even worse. While the current study didn’t specifically identify LED streetlight exposure, the lead study author, Maurice M. Ohayon, MD, DSc, PhD, director of the Stanford Sleep Epidemiology Research Center in Palo Alto, has publicly expressed his concerns over high-intensity LED street lamps that emit mostly blue light.


We humans are meant to sleep in the dark. Here’s how to bring it back…

If your town is even considering installing new LED lights, get involved and advocate that they install lower-intensity lights that are appropriate to the neighborhood. Bright lights aren’t always better. While they may make residents feel safer, the evidence is mixed over whether they actually reduce crime or even help prevent car crashes.

One compromise is for towns or cities to install blue LED lights (which help keep drivers alert) only in high-traffic areas. In residential areas, LED lights that throw a more yellow or orange light are more sleep friendly. That’s Dr. Ohayon’s recommendation. In Davis, California, for example, public outcry led to the replacement of LED lights that emitted very bright white/blue light to ones that emit a much warmer, yellower hue. (The correlated color temperature (CCT), a measure of color perception for different light intensities, was reduced from 4,000 to 2,700.) The city also installed house shields that block the light from intruding into homes. These alternatives tend to cost more, so public pressure may be needed to help public officials make the right call.

If lights outside your house are keeping you up, here are some suggestions…

  • Ask town officials to install house shields on your block.
  • Invest in room-darkening shades or curtains to keep the outside light out.
  • Sleep masks help, too.
  • If you like to wake up to morning sunshine and can afford a high-tech solution, put in dark shades and a programmable timer that will lift them early in the morning, suggests Apartment Therapy.
  • Be careful when installing lights outside your own home. Skip “globe” lights that spread glare in all directions, and make sure that any lighting you install doesn’t shine near your bedroom window.

Whatever you do, don’t ignore the light pollution outside your window. For a sleep-deprived nation, the steady march of super-bright LED street lamps should inspire a counter-movement to bring back the dark at night that we need for a good night’s sleep. For more advice on how to make your bedroom darker and more sleep-friendly, see Bottom Line’s article, “Is Your Bedroom Dark Enough?”—and get dozens of more ideas in this guide.