Well, this is oddly personal for hackernews but what the heck. This is pretty interesting to me. I’ve been living outdoors for the last 12 months, and I’ve noticed some significant changes in libido. It’s been on my mind quite a bit (not only for the obvious reasons but also wondering why this is happening to me). There’s a lot of factors of course, going from a mostly sedentary indoor life to a mostly actively outdoor life but this is fascinating. My SO is much more careful than I am with UV exposure and hasn’t seen the same change but again, too many factors to control for in this sort of anecdotal experience.
Slightly related: I've decided to stop using suncreen altogether for day-to-day sun exposure. My mood and overall sense of happiness increased significantly – in fact, it seemed to have helped more than my antidepressants ever did. (My libido did not increase but my antidepressants are pretty much libido killers.)
I don't put on sunscreen unless I know I will be outside unexposed for over an hour while the UV index is 5+. If I can wear a hat and long sleeves or know there will be shady spots, I still avoid sunscreen. I rarely get anything close to a burn and I believe this is probably healthier than the religious screen use that everyone seems to recommend.
Zinc oxide and titanium dioxide are the only two sunscreen ingredients the FDA considers truly safe sunscreen ingredients, and as someone with a basic understanding of biology, I tend to agree with them on this (1). Zinc oxide and titanium dioxide nanoparticles refuse to penetrate the skin even when rubbed into open wounds and they have negligible effects in vivo when used topically. Additionally and crucially they block UVA, the major skin cancer promoter, which won't give you sunburns. Zinc oxide is the most effective broad spectrum sunscreen. Titanium dioxide is less effective with UVA absorption. All other sunscreen compounds function after being absorbed into the skin. Unfortunately they also get into the bloodstream where they act as hormones such as estrogen mimickers (unintentionally).
The only downside of zinc oxide and titanium dioxide is that they are awful to apply (you need a good technique) and you will probably look awful after application. It may be better to apply less material at a time but more often. Most manufacturers recommend every 80 minutes. I think this is defined by FDA regulation.
Since zinc oxide and titanium dioxide are semiconductors, they can both reflect and absorb UV. I think there is a large gap in understanding by sunscreen manufacturers of how these nanoparticles perform on a quantum level. I hold out hope that some chemist can further engineer these nanoparticles perhaps through an innovative coating to further improve performance and appearance when applied. I think there is still a lot of money being left on the table and these compounds are under appreciated, not understood well, nor developed enough to this day. Fortunately the sunscreens containing them do work today.
Of all the metalic elements, Zinc is relatively harmless and actually has been shown to inhibit the process of viral replication.
By the way no one knows how elements behave on the quantum level we don’t have a quantum computer nearly powerful to simulate anything more than hydrogen
There are some relevant effects of UV on these semiconductor sunscreens to consider. For example:
It is generally agreed that UV absorption excites an electron from the valence band to the conduction band of the semiconductor. The resulting excited electrons, in the otherwise empty conduction band, and the “positive holes” in the valence band allow charge transfer to the TiO2 surface which facilitates oxidation of surrounding molecules. Sometimes direct charge-transfer causes the oxidation.
Some questions which stem from this finding include: what is being oxidized on the skin in its immediate vicinity when UV makes contact with the semiconductor sunscreen? What are the implications?
Is there any performance difference between nanoparticle sizes?
I mostly use zinc oxide sunscreen and don't think I look awful, which I understand is both a personal opinion and also something that can vary from person to person based on skin tone.
I’ve been seeing more and more evidence that we may not be getting enough UV exposure in general in the US. Vitamin D production is big, but what fewer people know about is nitric oxide which is also sythesized from UV exposure. It is a muscle relaxer that lowers blood pressure. It would undoubtedly have a positive effect on your mood.
I try to keep full spectrum light bulbs in as many rooms as possible within in my house, which also helps a bit, along with going outdoors as much as possible and supplementing vitamin D.
There is a whole lot of new conflict world wide out of the isolation and conservation that recent pandemics have caused. It's been a really frustrating missed opportunity by social and dating apps that they don't better help people to navigate social communication, scientifically based health advice, and relationship building/improvement with all the human isolation that is occurring and growing fast.
The term gonads though has always triggered Beavis and Butthead giggles for me ever since high school.
I haven't noticed any changes since I got back into hiking but I'm careful with the sunscreen--I live in the desert where the sun is brutal, any mistake is liable to result in a burn.
I have been seeing many hints recently that UV might be good for us in moderation but determining how much one is getting is problematic.
