Sleep Science • Article

Artificial Light at Night: Limit Harmful Effects on Sleep Health

Beth Levine

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Can't sleep? Tips for overcoming digital screens before bedtime. The artificial blue light they emit can negatively affect your sleep and wellbeing.


Laura Ketai, 72, Glastonbury, CT, was experiencing sleep problems for some time. She'd turn off the light, lie down and … nothing. It took her much too long to fall into a restful, undisrupted sleep.


One night, her husband suggested she read an actual book before bed, instead of her phone, as had become her habit.


“I slept so much better," she reports. She has now kept up the habit of staying off her phone before bed and while it hasn't eliminated all of her sleep issues, they are much improved.


What was the likely culprit? Blue light.


Why to Be Mindful of Blue Light Before Bed

Putting down gadgets may seem impossible. Oh, just one more text, one more Google search, one more round of this word game, you'll think.


But that often leads you down the rabbit hole and by the time you look up, an hour has gone by.


The Good and the Bad of Blue Light Absorption

Part of the sunlight spectrum, blue light surrounds you all day long.


It is what keeps you alert, boosts your moods and promotes cognitive function by suppressing melatonin, a hormone that promotes sleep. Its short wave length triggers sensors in the eyes to tell the brain to wake up.


At night, when the sun goes down and the blue light drops, your melatonin levels rise, telling you that it is time to go to bed.


Or that's how it's supposed to work, in theory.


In today's gadget-obsessed society, people spend much of their evening hours on blue light-

emitting devices such as smartphones, tablets and computers, which shifts your natural circadian rhythm, the body's biological clock.


“Exposure to blue light in the evening and late afternoon fools our bodies into thinking it's day and we should be awake," W. Christopher Winter, MD, President, Charlottesville Neurology and Sleep Medicine and author of "The Rested Child" and "The Sleep Solution."


As Ketai has discovered, this makes it difficult to fall asleep, reduces and delays the timing of important REM sleep and makes you less alert the following morning.


Blue Light Keeps You Sleepless in Seattle … and New York … and Atlanta … and …

How bad is the potential for sleep disruption if you're exposed to blue light in the evening? A survey conducted by found that:

  • 62% of participants say they sleep with their phone at night.

  • Participants spent an average of 50 minutes on their phones before bed.


And the trend is going towards more and longer device use, not less. In fact, the social isolation caused by the coronavirus pandemic has made media use even more pronounced, says a 2020 Italian study published in "The Journal of Sleep Research."


Researchers found that participants who upped their use of digital media were “going to bed and waking up later, and spending more time in bed, but, paradoxically, also reporting a lower sleep quality."


Reclaim Your Sleep Time – and Your Health

Quality sleep is critical to our wellbeing and fundamental to our health. Numerous studies have found that insufficient sleep can impact everything from weight gain to mood regulation to general brain health.


“Ongoing lack of quality sleep can have severe health consequences such as developing heart diseasetype 2 diabetesobesitydepression and anxiety." says Dr. Winter.


“There aren't real parameters for how much a decrease or increase of blue light is needed to gain a certain amount of melatonin release or decrease," he adds. "It can be measured by spectroscopes but we don't know yet what that measurement means in terms of sleep and wakefulness."


Here is how you can control your evening blue light exposure as much as possible:

  • The Sleep Number® smart bed features circadian rhythm tracking to help you track your sleep patterns.  It measures the duration, efficiency and timing of your sleep. Sleepers who are highly engaged with the bed’s SleepIQ® circadian rhythm feature improve their bedtime and wake time consistency by 30 minutes.*

Sleep Number® SleepIQ® technology helps you identify monthly sleep trends and offers actionable insights. You can analyze your sleep patterns and determine the ideal times to head to bed and when to wake up.

  • Get off digital gadgets at least two hours before bedtime. If you absolutely can't, download a sleep app such as f.lux that dims the screen light. Many devices come with these apps already installed such as Apple's Night Shift, which has been shown to cut blue light emissions by as much as 57%.

  • Wear blue light blocking glasses when you're in front of screens during the workday.


  • Instead of catching up on Facebook or playing games on your device before sleep, try simple yoga poses like these, meditation, a warm bath or reading an actual book. (While e-readers do not emit as much blue light as smartphones, they do emit some.)

  • Expose yourself to natural daylight during the day, and especially in the morning, and dim the lights an hour before bed in the evening to synchronize your circadian clock.

  • Use appropriate light during the day such as Sleep Number's Leo light therapy lamp, which mimics daylight during the day (without harmful UV light), which provides more daytime energy, improved focus and restful sleep at night.



“There are so many factors that go into whether I get a good night's sleep that it's hard to pin down to just one thing, but I think avoiding screen time leading up to bedtime has made a positive difference in my sleep," Ketai says.


Like diet and exercise, quality sleep is essential for optimal wellbeing and performance. Because everyone's sleep needs are different, Sleep Number® smart beds, with SleepIQ® technology inside, sense your movements and automatically adjust firmness, comfort and support to keep you both sleeping comfortably. Find your Sleep Number® setting for your best possible night's sleep


*Based on SleepIQ® data from 04/01/20 to 10/01/21 of sleepers who used the CR feature at least three times a week vs. those who did not use it.



Beth Levine is an award-winning veteran health writer whose work has been published in major media outlets such as, Good Housekeeping, Woman's Day, AARP Magazine and AARP Bulletin.

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