My experience is strangely different. I’ve read online that even the Queen of England takes Vitamin D. I’ve been taking different supplements and monitoring my bloodwork from time to time.
Vitamin D screwed with my sleep patterns. Apparently the vitamin is better absorbed at night. I’d have trouble staying asleep, and the quality of my sleep would plummet, when taking Vitamin D.
Poor sleep = weak immune system.
Sleep is an essential life-sustaining biological functions. Low quality sleep equals to a terrible immune system. I’ve been on and off the D a few times over the years, and it affected my sleep every time.
I had a period where I’d get sick every other week. The problem is that by the time it becomes serious you’re already used to being tired and looking pale with dark circles. You don’t notice that the stuff that was supposed to make you healthier is actually making you weak.
I’m taking vitamins D during winter, maybe once a week, sometimes, if I’m out of sunlight for too long. If you’re getting regular exposure to the sun, be careful with this vitamin (hormone).