Note that windows typically block the majority of the radiation that allows you to make vitamin D, so even if the sun hits you every day through your window, it's still not a good substitute for a sunny walk every once in a while. My doctor told me to go out at noon every day, but anything is better than nothing.

Yes, walking is super healthy, my lunch breaks are always a walk outside.

Walking doesn't help me for 8 months of the year: There simply isn't strong enough sun to help. December days are only 4-5 hours long anyway. So, I was told to take a supplement from September to May.

My doctor told me to get 15 minutes a day from May through the end of August - and these should be walks with at least the arms exposed (Am in Norway, so this isn't always possible for me, the immigrant). Walking alone isn't always enough.

I bought a load of UV-B flo tubes with a desert profile and rigged them up over my bed which would go upto the ceiling and then they would come down in order to bask under for hours. I could control how far away from me the lights were so I could move have them closer to me for a quick 30mins or have them further away for spending 2-3hrs underneath them.

I'd go to sleep under them, just dont have them too close to you though otherwise you will burn but never tan.

https://www.reptilecentre.com/collections/t5-uvb-fluorescent...

I'd also read this website entirely, its got loads of useful info. http://www.uvguide.co.uk/lightingsurveyintro.htm

Nearly all Glass and Plastics block UV-B which is needed to make Vit D. UV-A found in tanning salons oxidises the melanin pigment aka the sun tan and melanin converts 99.9% of UV radiation and converts it into heat, so the suntan regulates how much pre-vitD can be made by the skin.

There is a corrugated plastic sheet (2mx1m) which allows UV-B through, but it needs replacing every few years as it breaks down and its expensive!

Exposing your skin to the sun also creates nitric oxide. Hypothetically, that could also help mitigate cognitive decline (?)

Aren’t there like hundreds of physiological reactions to the sun? I think it helps on many levels.

Vitamin D3 also promotes osteoclastgenesis which can weaken the bones and release calcium into the blood stream.

Needs to be balanced with calcium. I wouldn't recommend supplements until you have blood work done.

You have to go really overboard with vitamin D3 to take too much of it. The daily recommendations so far are underestimating it. 4000 IU should be fine for adults. There are people that take 6000-10000 IU, but it's hard to say whether they might be suffering from some long term effects due to this.

You should take vitamin K2 with D3 though.

>But if you can be in the sun your skin can make vitamin D.

This is harder than people say. You need UVB light to hit your uncovered skin (glass blocks it entirely). The sun needs to be above 35-50 degrees in the sky. If it's below that (like in winter or evenings) then you won't get vitamin D from it.