Photobiomodulation Devices and Research

#21

I was listening to talks on this topic this weekend. The mechanisms are elusive but the effects are clearer. The red wavelengths have the effect of increasing ATP production…perhaps it has to do with effects on cellular water and/or a change in the mitochondrial membrane potential (charging the battery). Also interesting is how blue wavelengths have the opposite impact…it reduces ATP production. In the sunshine (all wavelengths) this all balances out. Indoors, with only blue light (LEDs) our mitochondria are less efficient (more ROS?). This would show up first in the cells that demand the most ATP…retina.

I am scheduling podcasts with people on this subject: Scott Zimmerman. Glen Jeffery. Other ideas?

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#22

The photobiomodulation study that got my attention was a randomized, double-blinded, placebo-controlled, split-face clinical trial from 2007.

It was the split-face design that I found compelling. They treated the right side of each participant’s face, but covered the left side so that it would remain untreated. This setup allowed for a within-subject comparison, where the treated and untreated sides could be directly compared for changes. The study also included a control group that received a sham light treatment.

Here’s what they found:

Among 76 participants, twice-weekly sessions of 633 nm red light therapy (totaling either 126 J/cm2or 44 J/cm2 depending on method of measurement) for four weeks reduced wrinkle severity (measured through average roughness) by 26% and melanin levels (measured through the Mexameter spectrometer) by 694%, while increasing gross elasticity by 14% (Lee et al. 2007). In all cases, no significant differences were seen on the within-patient covered side of the face or in the sham light control group.

The 19 participants who underwent biopsies displayed 1) an increase in the number of elastic fibers (Verhoeff-van Gieson stain; validated as normal with Alcian blue staining), 2) highly activated fibroblasts surrounded by thicker and more numerous collagen and elastic fibers (transmission electron microscopy), and 3) a 2.53-fold increase in Cx43 mRNA. For context, Cx43 is a gap junction protein that facilitates communication between cells.

There are plenty of other studies, but that one convinced me to purchase a smaller panel to use on my face. It’s a low-risk intervention with pretty good evidence—and it feels nice, too.

I would, however, mildly caution against using 830 nm near-infrared light (as opposed to ~633 nm red light) close to your hair. There’s a small amount of evidence that it can inhibit enzymes related to melanin production, which means 830 nm NIR could exacerbate graying hair.

In primary cultured human melanocytes and a 3D-mixed cell culture system, near-infrared (NIR) light at 830 nm (5, 10 and 20 J/cm2) reduced tyrosinase, TRP-1, TRP-2, and MITF—inhibiting melanin synthesis in vitro and ex vivo in a dose-dependent manner (Kim et al. 2012). LED irradiation at 850 nm has a similar, but attenuated effect on melanin production.

Seriously, though, this is just one study. So I weight it lightly.

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#23

On the other hand, 830 nm NIR will have significantly greater penetration. If used with an NIR helmet, it actually penetrates through the skull into the brain. The usefulness as a brain photobiomodulation intervention is a subject for another discussion.
For me, the subject of gray hair is a moot point.

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#24

I doubt this effect is significant because if it were, then people with a buzz cut that don’t wear a hat and stay out in the sun a lot would get gray hair from the infrared radiation from the sun, but this does not seem to be the case. In any case, if the mechanism of greying is merely inhibition of enzymes like tyrosinase, then the effect would be temporary and not a result of any permanent damage to the melanocytes.

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#25

FWIW, I have heard that people who spend a lot of time on submarines tend to get gray hair (& have few wrinkles). Google doesn’t have anything to say on this & I don’t remember where I heard it. I mainly remember looking at an ex-submariner & noticing his fully gray hair & smooth skin.

Pure rumor to you … :wink:

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#26

That makes sense. People spending a lot of time in a submarine should experience less skin photoaging form the lack of UV light exposure. At the same time they might get premature hair greying from all the stress involved in working on a submarine.

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#27

An excellent (and reassuring) point. Inhibiting enzymes related to melanin synthesis aren’t likely to affect the fundamental biology of graying hair (e.g. loss of melanocyte stem cells)—just orthogonally exacerbate attempts to hold off the gray.

The study dosed 830 nm NIR at 5, 10, and 20 J/cm2. Coming into this conversation, I honestly didn’t know how that compares to the NIR energy outputs we receive from the sun. So, out of curiosity, I visited Wolfram Alpha for some help.

  1. At solar noon, the irradiance is around 1000 W/m2 at ground level. This is the power per unit area from the Sun.
  2. The near-infrared (NIR) region (700–2500 nm) accounts for roughly 47% of solar irradiance. So, that puts the power from NIR light around 470 W/m2.
  3. At 830 nm, the solar spectral irradiance is around 1.5 W/m2/nm. So a 10 nm band around 830 nm (from 825 nm to 835 nm) yields 0.0015 W/cm2.
  4. Adding the element of time: 0.0015 W/cm2 × 3600s = 5.4 J/cm2 for one hour of peak sunlight exposure.

I wouldn’t put too much stock in that, but I wanted to get a general sense of scale. Based on those rough numbers, I’d say it’s reasonable to think that spending a few hours in direct peak sun could match the exposures from (Kim et al. 2012). In any case, I suspect it would require a bit of analysis to tease apart the ways sunlight exposure could contribute to hair pigmentation (including negatives like UV damage and positives like adequate vitamin D).

I didn’t mean to fall down this rabbit hole (and I’m not particularly concerned about NIR exposure for gray hair), but it is worth considering that these panels can deliver more energy of particular wavelengths than we’re likely to receive from the sun.

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#28

I got my knowledge on photobiomodulation from reading tons of studies on it, not from reading material from or listening to any particular experts, so unfortunately I don’t have a good idea of people to include in a podcast about it.

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#29

The estimate from Wolfran Alpha of 5.4 J/cm2 of 830 nm NIR for one hour of peak sunlight are not far off. In fact, the exposure from the sun can most likely be a good bit higher than that, in particular since you don’t just get 830 nm from the sun but also get longer wavelengths around 1000 nm that have the same effects and also penetrate deeply into the scalp. So yes, I do think that an hour in the sun when the sun is high can lead to an effective dose.