How blue light may impact your health and productivity

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The National Sleep Foundation has published the following guideline (hopefully I've included all appropriate age categories for Wealthy Affiliates):

  • Younger adults (18-25): 7-9 hours
  • Adults (26-64): 7-9 hours
  • Older adults (65+): 7-8 hours

In my previous life I recommended flex hours due to my staff and I working 16 hour days on a global application. I presented the following article which I don't think was received too kindly by my management. But that was then and this is now; you have your own business and can name your hours, right? Maybe, if this business is in addition to a regular job then this article is for you.

Yes this is a long read, you may wish to jump to the last section and then circle back for more info. Enjoy.

Jeff

Harvard Health Letter

Blue light has a dark sideExposure to blue light at night, emitted by electronics and energy-efficient lightbulbs, harmful to your health.

Until the advent of artificial lighting, the sun was the major source of lighting, and people spent their evenings in (relative) darkness. Now, in much of the world, evenings are illuminated, and we take our easy access to all those lumens pretty much for granted.

But we may be paying a price for basking in all that light. At night, light throws the body's biological clock—the circadian rhythm—out of whack. Sleep suffers. Worse, research shows that it may contribute to the causation of cancer, diabetes, heart disease, and obesity.

But not all colors of light have the same effect. Blue wavelengths—which are beneficial during daylight hours because they boost attention, reaction times, and mood—seem to be the most disruptive at night. And the proliferation of electronics with screens, as well as energy-efficient lighting, is increasing our exposure to blue wavelengths, especially after sundown.

Daily rhythms influenced by light

Everyone has slightly different circadian rhythms, but the average length is 24 and one-quarter hours. The circadian rhythm of people who stay up late is slightly longer, while the rhythms of earlier birds fall short of 24 hours. Dr. Charles Czeisler of Harvard Medical School showed, in 1981, that daylight keeps a person's internal clock aligned with the environment.

The health risks of nighttime light

Study after study has linked working the night shift and exposure to light at night to several types of cancer (breast, prostate), diabetes, heart disease, and obesity. It's not exactly clear why nighttime light exposure seems to be so bad for us. But we do know that exposure to light suppresses the secretion of melatonin, a hormone that influences circadian rhythms, and there's some experimental evidence (it's very preliminary) that lower melatonin levels might explain the association with cancer.

A Harvard study shed a little bit of light on the possible connection to diabetes and possibly obesity. The researchers put 10 people on a schedule that gradually shifted the timing of their circadian rhythms. Their blood sugar levels increased, throwing them into a prediabetic state, and levels of leptin, a hormone that leaves people feeling full after a meal, went down.

Even dim light can interfere with a person's circadian rhythm and melatonin secretion. A mere eight lux—a level of brightness exceeded by most table lamps and about twice that of a night light—has an effect, notes Stephen Lockley, a Harvard sleep researcher. Light at night is part of the reason so many people don't get enough sleep, says Lockley, and researchers have linked short sleep to increased risk for depression, as well as diabetes and cardiovascular problems.

The power of the blues

While light of any kind can suppress the secretion of melatonin, blue light at night does so more powerfully. Harvard researchers and their colleagues conducted an experiment comparing the effects of 6.5 hours of exposure to blue light to exposure to green light of comparable brightness. The blue light suppressed melatonin for about twice as long as the green light and shifted circadian rhythms by twice as much (3 hours vs. 1.5 hours).

In another study of blue light, researchers at the University of Toronto compared the melatonin levels of people exposed to bright indoor light who were wearing blue-light–blocking goggles to people exposed to regular dim light without wearing goggles. The fact that the levels of the hormone were about the same in the two groups strengthens the hypothesis that blue light is a potent suppressor of melatonin. It also suggests that shift workers and night owls could perhaps protect themselves if they wore eyewear that blocks blue light. Inexpensive sunglasses with orange-tinted lenses block blue light, but they also block other colors, so they're not suitable for use indoors at night. Glasses that block out only blue light can cost up to $80.

Less-blue light

If blue light does have adverse health effects, then environmental concerns, and the quest for energy-efficient lighting, could be at odds with personal health. Those curlicue compact fluorescent lightbulbs and LED lights are much more energy-efficient than the old-fashioned incandescent lightbulbs we grew up with. But they also tend to produce more blue light.

The physics of fluorescent lights can't be changed, but coatings inside the bulbs can be so they produce a warmer, less blue light. LED lights are more efficient than fluorescent lights, but they also produce a fair amount of light in the blue spectrum. Richard Hansler, a light researcher at John Carroll University in Cleveland, notes that ordinary incandescent lights also produce some blue light, although less than most fluorescent lightbulbs.

What you can do

  • Use dim red lights for night lights. Red light has the least power to shift circadian rhythm and suppress melatonin.
  • Avoid looking at bright screens beginning two to three hours before bed.
  • If you work a night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses or installing an app that filters the blue/green wavelength at night.
  • Expose yourself to lots of bright light during the day, which will boost your ability to sleep at night, as well as your mood and alertness during daylight.

image: © Innovatedcaptures | Dreamstime.com

Updated: September 2, 2015

Originally published: May 2012

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Recent Comments

37

Very interesting Jeff, thanks :)

YW

Hi Jef, excellent advice on blue light. Irv.

Thank you.

Right on, Jeff. This is one of the best posts I've read since I've been here. I am, and always have been, most comfortable in total BLACKNESS while sleeping, it's just the way I am. But you have reinforced the point my mom made 8 years ago after the birth of my daughter..."NEVER LET HER FALL ASLEEP IN FRONT OF THE F#CKING TV!!!!!!!". Most educational bud, thank you.

Happy you enjoyed it.

HI Jeff-
very informative. I am closing my computer now before it is too late :) Thank you for sharing.

YW, glad you liked it.

Great article Jeff!

I find that I sleep so much better when my room is as close to pitch black as possible, so my drapea are extra thick. Although I'm not much for checking my phone once I lay down, I've read before about the importance of allowing a couple of hours after using the TV, laptop or phone, before going to sleep. Gotta work on that one...

You and me both, take care.

Hi Jeff,
This is great information. I didn't realize that computer light would keep you awake, very interesting. I do my best to turn off the computer around 9:00 pm, or so. It make a lot of sense. Thanks for your insight. Have a good evening.
Mary

Thanks Mary.

Thanks for this information. I try not to read in bed and if I do I get up and use regular light source.

Good for you.

I've investigated this myself, and on my amazon affiliate website I have a post that leads someone to buying UV blocking glasses or clip ons. (I have a pair).
And recently, in an eye exam, the doc told me "keep wearing those computer glasses!". And I do.

In my home, my night lights are Himalayan Salt lamps. Nice orange light!

Great post!

Thanks, I'm going to pick up a pair of the clip ons - what do you recommend?

http://bestcheap-ereader.com/computer-reading-glasses

scroll down there are 2 clip ons, the cheaper one is $29.95. That's my affiliate link, but you can get the info and then get it from amazon without my link...since you're my pal here!

Thanks.

Good post, Jeff.

Thanks.

Great share thanks,

Thank you for reading it Mike.

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