OW. My head is aching with all this "melanin" "melatonin" stuff. Like "apple" and "pineapple", they sound the same, but are entirely different things!

So just to clarify, the reason why we could BURN more wearing sunglasses is cuz the eyes would be shielded from the sun, thus preventing the pituitary gland from producing melanocyte-stimulating hormone (MSH) that would ultimately produce melanin to darken our skin. Our pale skin (blue white, in my case) would then be WIDE open to burning under the sun's rays.

Well, sunglasses or not, it's going to be the 12th of never before I can even think about playing in the sun at 6500': hiking, biking, swimming, sitting in my inner tube, all that is going to have to be done under my new, reflective white burqa. I am bummed.

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I Bug U

It's produced by the pineal gland. But some bone cells can also produce it.

[Apparently you can get less tanned by wearing sun glasses as it causes the optic nerve to get less sunlight ---I quote the last paragraph]

They didn't provide any references.

IWhen light enters your eyes, it triggers your pituitary gland to produce a melanocyte-stimulating hormone (MSH) that activates your melanocytes to produce melanin. This means that wearing sunglasses can actually cause sunburn.


Yes the pituitary does produce MSH. But mammals have the tanning response even without immediate UV radiation on the eyes, i.e. it doesn't have to occur at the same time the skin is exposed for the skin to tan--there is some melanin reservoir there to respond in people who have the appropriate intrinsic pigmentation. I don't know how much more or less that momentary light matters. I do know that we can damage our eyes with exposure to UV and we need sunglasses, too.

[however I got similar answers regarding the relationship between the optic nerve and melanin in other "more erudite" articles - LOL]

Well, it is true that MSH will increase in plasma levels with UV light is shined in the eyes. But the skin has a reservoir of MSH so there is enough there to generate a tanning response without concomitant UV radiation entering the optic nerve.

I found this:
http://www.nature.com/jid/journal/v120/n1/full/5601715a.html

Here they found that if the eye but not the ear was stimulated with UV radiation, the ear got darker. They also found that if the ear but not the eye was stimulated with UV radiation, the ear got darker. The ears darkened about the same amount per dose of UV radiation.

They did not test the situation where both ear and eye got UV radiation simultaneously.

So this study does not suggest that sunglasses inhibit the tanning response. I suspect that's an extrapolation for now.

Lara did us a favor by bringing up the MSH issue. But now I am thinking about the tanning issue. The tanning response is not from melanin synthesis but occurs when melanin in the skin gets oxidized (protecting the skin from the oxidation itself), polymerizes, and the melanosomes redistribute. Much of this happens hours to days after exposure. Other events also occur such as increased expression of destructive enzymes that break down collagen. A tan provides SPF and PPD of around 2. But a good sunscreen can provide much more protection than that.

So I don't think not wearing sunglasses is a good idea. Already we know it's not a good idea because it can lead to cataracts, macular degeneration, etc.

But sun exposure does have some benefits. You can always get your vitamin D from a pill but I don't think there's an equivalent way to elevate mood in the way that sun does without UV radiation. If you are one of those people who suffers from Seasonal Affective Disorder, you will have to protect yourself as much as you can while you get your happy dose. And for that, you do need the eye entry.