Photo

Wired Well Personal technology for health and fitness.

Most evenings, before watching late-night comedy or reading emails on his phone, Matt Nicoletti puts on a pair of orange-colored glasses that he bought for $8 off the Internet.

“My girlfriend thinks I look ridiculous in them,” he said. But Mr. Nicoletti, a 30-year-old hospitality consultant in Denver, insists that the glasses, which can block certain wavelengths of light emitted by electronic screens, make it easier to sleep.

Studies have shown that such light, especially from the blue part of the spectrum, inhibits the body’s production of melatonin, a hormone that helps people fall asleep. Options are growing for blocking blue light, though experts caution that few have been adequately tested for effectiveness and the best solution remains avoiding brightly lit electronics at night.



Wired Well The Well Guide to Activity Trackers We tested some of the latest and most popular trackers to compare how they work and the various features they offer. Here’s what we found.

Wired Well What Your Activity Tracker Sees and Doesn’t See High-tech fitness and activity trackers all share one thing: an accelerometer. Here’s how they work — and don’t.



A Swiss study of 13 teenage boys, published in August in The Journal of Adolescent Health, showed that when the boys donned orange-tinted glasses, also known as blue blockers and shown to prevent melatonin suppression, in the evening for a week, they felt “significantly more sleepy” than when they wore clear glasses. The boys looked at their screens, as teenagers tend to do, for at least a few hours on average before going to bed, and were monitored in the lab.

Older adults may be less affected by blue light, experts say, since the yellowing of the lens and other changes in the aging eye filter out increasing amounts of blue light. But blue light remains a problem for most people, and an earlier study of 20 adults ages 18 to 68 found that those who wore amber-tinted glasses for three hours before bed improved their sleep quality considerably relative to a control group that wore yellow-tinted lenses, which blocked only ultraviolet light.

Devices such as smartphones and tablets are often illuminated by light-emitting diodes, or LEDs, that tend to emit more blue light than incandescent products. Televisions with LED backlighting are another source of blue light, though because they are typically viewed from much farther away than small screens like phones, they may have less of an effect, said Debra Skene, a professor of neuroendocrinology at the University of Surrey in England.

LEDs are also increasingly popular as room lights, but “warm white” bulbs, with less blue, tend to be a better choice than “cool white” for nighttime use. The lighting company Philips also makes a bulb, called Hue, that can change the intensity of its component colors via an app, and GE last month announced a reduced-blue LED bulb, meant to be used before bedtime.

Photo

“Conceptually, anything that will decrease that blue light exposure at night will be helpful,” said Christopher Colwell, a neuroscientist at the University of California, Los Angeles. “I know some gamers who swear by those orange-tinted goggles.”

But orange glasses are not a panacea, Dr. Skene said. “It isn’t just get rid of the blue and everything’s fine,” she said. The intensity of light, in addition to color, can affect sleep, she said, and not all brands of orange-tinted glasses have undergone enough independent testing for their ability to aid sleep.

Screens that are not backlit, such as some e-book readers, are preferable to typical brightly lit screens, Dr. Skene said.

Mr. Nicoletti says that the orange glasses he wears, an industrial-safety brand called Uvex, do make some colors, notably blues and greens, harder to distinguish. He also uses applications designed to alter the blue light impact of his devices depending on the time of day: an app called f.lux for his computer and Twilight for his mobile phone.

Other ideas are proliferating. An Ohio company called LowBlueLights.com, for example, offers filters said to block blue light by covering the screens of electronic devices like the iPhone or iPad. Other company products include “low blue” LED lights and orange eyewear.

During the daytime, experts say, exposure to blue light is good. Best of all is sunlight, which contains many different wavelengths of light. “That’s what our brain knows,” said Kenneth P. Wright Jr., director of the sleep and chronobiology lab at the University of Colorado, Boulder.

A 2013 study he led, published in the journal Current Biology, showed just how different things can be without nighttime lights: After participants had camped in the mountains for a week, their bodies began to prepare for sleep about two hours earlier than normal.

Short of cutting out all evening electronics, experts say, it’s advisable to use a small screen rather than a large one; dim the screen and keep it as far away from the eyes as possible; and reduce the amount of time spent reading the device.

“If you can look at the iPhone for 10 minutes rather than three hours, that makes a lot of difference,” Dr. Skene said.

Look for more Wired Well stories, Tuesdays at nytimes.com/well

Related:



For more fitness, food and wellness news, “like” our Facebook page.