Tag Archives: blue light

The dark side of blue light – Harvard

Elsewhere in the blog I have written repeatedly about the how valuable it is to get a good night’s sleep. For a full rundown, please check out my Page – How important is a good night’s sleep?

In the meantime, here is an excellent study from Harvard Medical School on our vulnerability to our evening illumination.

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Exposure 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. Continue reading

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Beware of blue light at night – Harvard

Sleep, like walking, is one of the critical elements of good health very commonly not appreciated by the man on the street. I have a Page – How important is a good night’s sleep with a ton of information on it.

Here is some valuable info from the Harvard Health Letter on getting a good night’s sleep.

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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. (My emphasis)

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.When I work on my computer late at night, I always wear a pair of blue blocker sunglasses. You can buy them on Amazon for under $20. I have no problems getting to sleep.

    Tony

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Can Early Morning Sunlight Help You Lose Weight?

Early to bed, early to rise makes a man healthy, wealthy and wise, Ben Franklin. famously said.  If that man gets himself outside in the early morning sun, he may also enjoy other substantially healthy benefits.

I was excited to learn that while I am out riding in the early morning sun, I will be enjoying some other very healthy benefits.

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Dr. Phyllis Zee and other researchers from Northwestern Memorial’s Feinberg School of Medicine recently published a study showing in effect that morning sunlight makes you healthier.

According to the study “Light exposure can influence sleep and circadian timing, both of which have been shown to influence weight regulation.”

The early morning sun affects hormones that regulate appetite and neurotransmitters that regulate the sleep/wake cycle.

The early morning bright lights also wake us and lift our mood which may prompt us to make healthier decisions through the rest of the day.

The study included 54 people for an entire week. Those who spent more time in early morning sunlight were leaner than the ones who got their light exposure later in the day.

Dr. Zee said that the early morning light has more blue which is a more powerful stimulus for your brain. This compares with the red and orange light that we tend to get later in the afternoon.

In case you didn’t know, blue light is melatonin-suppressant. Melatonin is the hormone that starts to put us to sleep. If it is suppressed, we don’t feel as tired and will not fall asleep very easily.

So get out there and get some of those early morning rays. You will start your day on a positive note and feel better the rest of the day.

On the other end of the time spectrum, I have recently learned that TV screens, iPads and computers emit a lot of blue light. That is why working on your computer just before going to bed can make it more difficult to fall asleep. I wear blue blocker sunglasses when I work on my computer late to keep it from interfering with my falling asleep. They seem to work.

Tony

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