Came across an interesting fact that I've never seen mentioned in relation to cluster headaches - our apparent natural "biphasic" sleep pattern which was common up until the industrial revolution. It varied across populations but in this particular article is referred to as:
"between 9 and 10pm, slept for 3 to 3 ½ hours during their “first sleep,” awakened after midnight for an hour or so, during which individuals did practically anything and everything imaginable before taking a “second sleep,” roughly until dawn."
https://www.news-medical.net/news/20170517/History-of-sleep-what-was-normal.aspx
This just so happens to coincide with the 1am wake cycle most CH suffers experience. When at the peak of my worst cycles I also commonly get 9-10pm and 6-7am attacks, which slot in nicely to the start and end of the bi-phasic sleep period.
It appears through a study in the 1990s that this may be the most natural sleep/wake cycle for our brains (see https://en.wikipedia.org/wiki/Thomas_Wehr)
I find it hard to believe that this is just a coincidence. Has anyone else come across this aspect of sleep behaviour in relation to CH? It may be a piece of the puzzle as it is very much governed by melatonin from what I've read so far.