Blue Light: Bad for Sleep but Good for Heart Health?

Feb 24, 2019 | Greggory Moore | Moore Lowdown
Blue Light: Bad for Sleep but Good for Heart Health?

image by: Christina Morillo

Blue light has gotten a bad rap in recent years, but new research suggests that a different sort of exposure than you get from your electronic devices may help with high blood pressure and more.

Blue light. You hadn't even heard the term until a few years ago, when scientists started warning you that exposure to blue light just before bedtime might be negatively impacting your sleep. And although by now you've read enough to know blue light emanates from smartphones and computers, let's be honest: you don't really know what it is. Which makes it doubly confusing for you to hear that now scientists are saying blue light might be good for your cardiovascular system.

But we're getting ahead of ourselves. Let's define what we're talking about. Visible light is the range of energy on the electromagnetic spectrum that our eyes are able to register. Remember the mnemonic "ROYGBIV" from your high-school science class? That was to help you keep in mind the visible portion of that spectrum, which our eyes register as Red, Orange, Yellow, Green, Blue, Indigo, and Violet. The "red" end (ROY) of the spectrum of visible light has the lowest wavelength, while the "blue" end (BIV⎯and yes, it is more consistent to call it "violet light") has the highest. (This may help you understand why you get a sunburn from ultraviolet (meaning "beyond violet") radiation but not infrared ("below red") radiation, even though the sun gives off both: UV radiation is more intense.)

As Harvard University neuroscientist Anne-Marie Chang told Scientific American in 2015, "Recent studies have shown that short-wavelength [blue] light has a greater effect on phase shifting the circadian clock and on melatonin suppression." And since you've already heard that computer screens, smartphones, and other such electronic devices emit large amounts of blue light, as long as you know that melatonin is the hormone that regulates your sleep-wake cycle, you get the point without our having to get into how the eye has to work harder to focus on light at the violet end of the spectrum.

But there's more to the body than just the eyes, and it's exposing the rest to "blue" light that may benefit heart health. As reported in a paper published in the November 2018 edition of the European Journal of Preventive Cardiology, research conducted suggests that a 30-minute daily dose of whole-body exposure (imagine a tanning bed, except one that emits visible "blue" light rather than UV radiation)⎯equivalent to the exposure one gets from a full day out in the sun⎯lowers blood pressure and increases blood levels of nitric oxide, a cardiovascular protectant.

According to a press release issued by the University of Surrey, "Besides blood pressure lowering effects, it was also uncovered that exposure to blue light improved other cardiovascular risk markers including reduction of arterial stiffness and increasing blood vessel relaxation. This further supports that light could be used to prevent cardiovascular disease, which kills over 150,000 people in the UK every year."

The potential suggested by these results is that such exposure may turn out to be a viable alternative to some medications. "Exposure to blue light provides an innovative method to precisely control blood pressure without drugs. Wearable blue light sources could make continued exposure to light possible and practical," says Christian Heiss, one of the paper's co-authors. "This would be particularly helpful to those whose blood pressure is not easily controlled by medication, such as older people."

While usually the side effects blood pressure medications are not particularly serious, no side effect is good. Moreover, the more medications you take, the more potential problems you have with contraindications, and the harder it is generally on your body⎯particularly your liver, through which all medications are processed.

This is why the new findings about "blue" light are so intriguing. In the foreseeable future, simply shining light on your body may benefit your cardiovascular health while sparing your body unnecessary strain.

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