Life hack for better sleep: Reduce Blue Light exposure at night
We all know UV light (ultra-violet) is harmful to our eyes, but did you know that blue-violet light (emitted with from artificial sources or the sun) can also cause health issues? With our kids all using Chromebooks or other tablets for school work in and out of class, they are being exposed to a lot more screen time than they were even 5 years ago. In a Harvard article Blue Light has a Dark Side, their research shows a strong link between evening blue light exposure and poor sleep. We’re finding that our kids are more susceptible to this effect than adults, so much so that the American Medical Association deems this a public health issue.
Until 1879, when the light bulb was invented, human beings have had very limited amounts of light to use at night and most of us would be limited to being awake when the sun was up and asleep at night when the sun was down. You’ve likely heard of circadian rhythms, aka your body’s clock, and that they regulate our sleep-wake cycle, but it turns out that the circadian system is more like a fancy a blue light detector. Using the eyes, the body is looking for blue skies to know when to wake up. The circadian system uses the brightness of sky to stimulate alertness and wake us up long before we had alarm clocks. Before the light bulb, we only had fire to help light the night. Flames from hearths or candles emit light along the red side of the spectrum (hence why they look red or orange to us). These interfere very little with the brain’s ability to regulate the sleep hormone melatonin.
The down side of blue & violet colored light (380-450µm), even at low intensity, is that it significantly suppresses melatonin production, the chemical that helps you feel ready to sleep. This effect continues a full hour after we stop exposing ourselves to the blue light source. This means if we use computers, tablets or smart phone until we want to sleep, our bodies will have a hard time falling asleep and getting restful sleep. We also tend to stay awake longer due to the increased alertness from the light’s stimulating effect on the brain. These wavelengths stimulate your brain to stay alert better than caffeine!
Camping with limited access to devices and electric lights is great way to demonstrate the power of this effect. Even if you’re normally a night owl, you’d find it easier to wake up earlier; after about 2 weeks you’ll wake with the sun feeling refreshed, having successfully reset your body’s clock.
Importance of sleep is to make ‘wake’ worthwhile. The body is looking for a very bright signal during the day and a very low signal at night, but when we spend a lot of time indoors, and use devices at night, we are exposed to a consistent signal all the time, which is neither bright nor dim but lies in the middle somewhere. This stimulation will extend the day and reduce or halt the production of melatonin. Without this hormone, you won’t feel like you are sleepy or ready to go to bed. The good and bad side to the blue side of the spectrum is that we can use it to make us feel more alert during the day, but it also doesn’t allow us to wind down at night.
So what can we do to improve our sleep? Remove all LEDs and LCD screens (smart phones, TVs, computers) from our lives? I certainly am not ready to give up mine. Remove the blue light from our devices giving our screens a permanent state of yellowy-orange hue? Also a bad idea, as the bright white of the screen is helping me be alert while I write this blog at 9 am. A balance is key to any successful change.
The very same technology that is causing the sleep problems can be used to help you catch those all-important Z’s. The simplest solution, besides discontinuing screen time an hour before bed, is using a selective filter program. My favorite program (F.Lux) will automatically monitor the time and select how much blue light should be emitted. So if I’m writing at 9 am there is no filter and my screen looks bright white; at 9 pm my screen is tinted very orange. I’ve been using this for a while and feels calming to look at in the evening. There are variations for android called twilight, but it doesn’t work quite as well as the one I have on my PC (F.Lux works on Apple devices too, but requires some simple modification). See what colors of light your specific device gives off here.
If you are unable to modify your devices (due to a school or work limitation), I recommend wearing glasses that filter out some or all of the blue-violet light. If you find that you must use a device for the hours preceding sleep, then a pair of glasses that block more of those rays can be helpful. This pair of glasses is designed specifically for nighttime device usage. Although you could wear them all the time, these lenses have a yellow tint, like BluTech or Gunnar lenses for example.
During the day, I recommend wearing your normal glasses with a special coating to block some of the blue-violet light all the time. My patients find it more comfortable to work at the computer all day with 25% blocked when compared to normal glasses without the coating. Their glasses are still clear and only block the specific wavelengths that are over stimulating the circadian system.
The benefit of reducing this spectrum is beyond just melatonin effects, it also reduces scatter from the light emitted from the computer monitor. The shorter the wavelength, the more light will scatter inside the eye, and blue-violet colors are much shorter than orange-red colors. Reducing scatter has the effect of sharpening the image quality on the retina inside the eye. Clearer images lead to less eye strain, which makes many people more comfortable while using a device. Because of this reduction in eye strain, I recommend this type of lens to be worn all day for those using devices 3+ hours/day. 67% of millennials use devices 5+ hours/day and those younger, including our kids, are not much behind them; this leads to a lot of eye strain, in fact 73% of those under 30 experience digital eye strain symptoms.
If you think your child is having a hard time in school, it may just be too much time spent on electronics before bed. The AMA report (linked above) shows that reducing screen time before bed improves quality of sleep (defined as more time spent in REM sleep) as well as helps the students focus better in school the next day. It recommends that if you or your kids are unable to reduce time spent with devices, that you consider glasses that block a greater percentage of blue light for the 2-3 hours before bedtime. With our school district issuing Chromebooks to all our students, I want to ensure our students have the best possible chance to be successful and quality sleep is a good place to start. **
**Although this article focuses on how blue light affects our kids, reducing screen time before bed is also advantageous for adults. Mostly though improving sleep cycles, we see reduced risk of cancer (especially breast cancer), lower risk of developing macular degeneration and improving sleep quality.
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Posted April 2016 by Laura Nennig, OD; she specializes in contact lens fittings, with advanced training with scleral lenses.
