Blue light interferes with sleep and melatonin secretion at night but is beneficial during the dayBlue light gets a bad rap these days in articles about sleepy teens. Exposure to blue light in the evening interferes with the secretion of melatonin (a sleep-friendly hormone), pushing circadian rhythms out of whack. This can lead to insomnia or sleep deprivation. Doctors are counseling teens and the rest of us to turn off devices that emit blue light—computers, tablets, and smartphones—in the run-up to bedtime.

This is sound advice as far as it goes. But the story on light is bigger than this simple warning suggests. Knowing how to manage your exposure to blue light can help you steer clear of sleep problems and increase your daytime stamina.

“I Play Solitaire on My iPad at Night”

Screen time at night not just a temptation for teens. A grandmother I met the other day wondered if playing solitaire on her iPad in the middle of the night was contributing to her insomnia and making it harder to fall back to sleep.

I replied that it might be. Humans are most sensitive to the effects of blue light when our brains least expect it: late in the evening, at night, and early in the morning. The most intensive source of blue light is the sun. But the self-luminous screens of computers, iPads and iPhones emit blue light, too, at wavelengths that suppress melatonin. TV screens also emit blue light. But proximity to a light source matters. We position ourselves much closer to handheld devices and computers than we do to TVs, so the newer devices are more likely to interfere with sleep.

There’s an App for That

If you can’t bear to part with your iPad at night, there are ways to protect yourself from the light it emits. Dr. Craig Canapari recently posted an article containing helpful advice, and I’ll summarize it here:

  • Manually dim screens on devices at night
  • Visit Just Get Flux to download free software that automatically adjusts the color temperature of your computer screen according to the time of day
  • Get “night mode” software for your tablet or smartphone. The display will appear as white text on a black background.

You can also wear blue light-blocking glasses at night. A new study of teens shows that blue-blocker glasses with orange lenses allow for normal melatonin secretion and sleepiness to develop at night regardless of time spent looking at screens. But expect to pay more for these glasses than for a cheap pair of sunglasses with orange lenses. Cheap glasses will block blue light and other colors, too, so they won’t work well indoors.

Last but not least, use dim red lights as nightlights. Red light is least likely to suppress melatonin secretion and shift the rhythms of your body clock.

Soak Up the Rays During the Day

In the daytime, on the other hand, exposure to blue light is beneficial. Not only does it boost your attention, speed your reaction time and elevate your mood. It also helps you maintain a regular sleep/wake cycle.

But as the days grow shorter, you may miss out on daily exposure to the sun, a critical source of blue light. If you work in a windowless office, warehouse, or power plant and you commute in the dark, the daily resetting of your body clock enabled by sunlight does not have a chance to occur. Your circadian rhythms may go off track and your sleep take a turn for the worse.

A study just published in PLoS One illustrates this neatly. It was conducted at a polar base station at a time of year when crew members got no daily exposure to sunlight. Here’s what the researchers found:

  • When the subjects were working in standard indoor lighting for 2 weeks, they experienced a significant, 30-minute delay of melatonin secretion in the evening, and a decrease in sleep duration.
  • Working in blue-enriched white light for 2 weeks, they did not experience the delay in melatonin secretion. They slept longer and experienced a greater sense of wellbeing and alertness during the day. Daily exposure to blue-enriched light made the difference.

If you regularly miss out on the sun, consider investing in a light box, which will give you the daily dose of blue light your body needs. Better yet (but maybe something of a long shot), suggest the installation of blue-enriched white light at your workplace. The fact that it enhances work performance could sweeten the idea for the boss.

Have you noticed a seasonal pattern to your insomnia, where in the wintertime it tends to grow worse?

Posted by Lois Maharg, The Savvy Insomniac

Lois Maharg has worked with language for many years. She taught ESL, coauthored two textbooks, and then became a reporter, writing about health, education, government, Latino affairs, and food. Her lifelong struggle with insomnia and interest in investigative reporting motivated her to write a book, The Savvy Insomniac: A Personal Journey through Science to Better Sleep. She now freelances as an editor and copy writer at On the Mark Editing.


  1. Thanks for the shout out! Terrific article.



    1. Dr. Canapari,

      You’re certainly welcome for the mention. Compliments to you for the fine article you wrote last month!



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