I've been struggling with insomnia for a very long time. I was having trouble falling asleep, and when I woke up, I'd feel tired. I complained to my doctor about it, and she prescribed something and then switched me over to another medication later...

Two years later, she suggested that I have a vitamin D blood test. Apparently, I've had an extreme deficiency this whole time! The bare minimum is 20 ng/mL. Some experts recommend levels between 30 ng/mL and 50 ng/mL, and I was at 7.03 ng/mL!

I wondered how that even happened. I know there aren't a lot of sunny days in our latitude, and I spend a lot of time indoors, but I had been taking supplements from time to time. They should've done something, right? I was taking them according to the instructions in the little paper insert: 500 IU/day. But that's way too low — even doctors say that this is an outdated standard and the recommended dosage in the package insert should be higher. Some doctors recommend taking up to 4000 IU/day just as a maintenance dose. And when you have a severe deficiency, you should take up to 10,000 IU per day!

My doctor prescribed 8000 IU/day of vitamin D, and I felt much better in just a week. It didn't magically cure all my problems, but I did feel an improvement in my energy levels.

Vitamin D is a very important nutrient. It affects the strength of our bones, our sleep quality, and even our mood. I broke a bone once, had poor sleep quality, and my mood used to swing like a roller coaster. And it's not an uncommon problem to have a vitamin D deficiency, especially in northern latitudes. In Russia, according to one study, 89% of people ages 18–25 have insufficient levels of vitamin D. In the UK, according to another study, 12% of white participants, 35% of black participants, and 53% of Asian participants ages 40–69 had a vitamin D deficiency. I heard that in Canada, doctors don't even send you to do blood work, they just prescribe a vitamin D supplement right away because the deficiency is so common. I wonder why it took two years for my doctor to check me...

Two months after I started taking supplements, I had another blood test, and now I'm at 61.20 ng/mL of vitamin D. I was surprised by this result because I'd heard that people have trouble raising their vitamin D levels. I guess they have other health issues that cause problems with vitamin D absorption such as stomach illnesses or being overweight. Now I'm going to reduce my daily vitamin D intake.

I can't talk about taking supplements without mentioning some of the risks involved. Vitamin D depletes your magnesium levels, so you should take magnesium supplements as well. There's also vitamin K2, which prevents arterial calcification, which you should also take. My doctor didn't even mention that — I had to do the research myself. Vitamin D overdoses can be harmful and even fatal. In February, an elderly man in the UK died from a vitamin D overdose. He'd been taking it for at least nine months. There's no information about how much he was taking. Some studies suggest that taking up to 10,000 IU per day for a period up to six months should be perfectly safe. But it's better to check your vitamin D levels before and after taking supplements. And remember, I'm not a doctor — I'm just a guy talking about my own experience.