I am currently in the middle of a CH season. A couple of weeks into it I discovered I was only taking 1/2 dose of vitamin D3. I had not read anything about the effects d3 has on cluster headaches. I doubled the dose and didn't have another CH for 5 days. On the 5th day I felt another CH coming on so I took another dose. The CH went away and I continue to take 2 doses a day. 1 in the AM and 1 before bed. That's 200mcg per day. Hope this helps