Seth Roberts has been collecting anecdotes from people taking vitamin D in the early morning and reporting improved sleep. He thinks the body might interpret it like sunlight.
Robb Wolf, on the other hand, finds that taking VD3 at night works best for him.
What factors determine whether one will get better results from taking VD3 in either the early morning or evening?
I got the idea from Tara Grant. Her sleep instantly improved when she started taking Vitamin D3 first thing in the morning instead of mid-afternoon or early evening.
Interesting - I can't see evolutionionary reasons for either. I'm always careful to take mine as close to solar noon as possible - and only on days I've not had adequate sun exposure
I had trouble sleeping when I started Paleo and was taking my D3 at night before bed. Was nervous and couldn't seem to settle down. No problems since I went to morning, I have them with my fish oil right after breakfast.
After hearing Robb's podcast I switched my Vit D to night along with my Mg. MUCH better sleep. It's like I just pass out and don't remember the night at all and I wake up refreshed. There is probably no single right answer for everyone; and, it's so simple to test for yourself, that you should just do a week both ways and see what works best for you.
Knowing Robb's schedule and how busy he is I bet he is telling the truth about D3 better at night for him because his circadian rhythms are pretty screwed up secondary to his neolithic life.
I tried taking vitamin D the evening first, and I was pretty anxious and could not sleep even with only 2000 iu/day. I switched to morning in past 2 weeks and I have been sleeping like a baby ever since. I think my explanation for sleep disturbance is that the fillers in vitamin D supplements could be the culprit rather than the vitamin D itself. I have bumped my daily intake to 5000 this past week and it seems to be working.