It is from Tara Grant, a California journalist whom I met at the 2011 Ancestral Health Symposium, that I got the idea that the time of day you take Vitamin D3 matters (morning good, evening bad). She recently wrote more about her experience:
I had never had a sleep problem growing up, or during my 20s or early 30s. I kept a regular sleep cycle, woke up rested, preformed well in school and never needed to have naps. However, when I was in my mid-to-late 30s, the sleep problems started. [She woke up many times per night.] This was around the same time I went Primal and adopted several changes in my diet and lifestyle, including taking supplements. One of those supplements was Vitamin D3 [10,000 IU/day], something I had never taken before.
The sleep problems persisted for a couple of years. When I changed the time of day I took my Vitamin D [making sure to take it in the morning, never in the evening], they resolved. I didn’t change anything else, as I didn’t need to.
My experience has been that Vitamin D3 in the morning improved my sleep and that the dose needed to get this improvement was more than 2000 IU. Doses of 4000 IU and more were effective. More than 20 people have had similar experiences. A few people have found that Vitamin D3 in the morning did not improve their sleep.