One thing I’ve always found quite odd about it is that I suffered from horrible gut problems for the first 30 years of my life. Turned out it was wheat (or whatever passes for that in the US) causing a massive amount of inflammation in my body. Once I figured this out and got it under control is when my sleep patterns really locked into the 6 hour routine. I’d be curious to understand how it might be linked. I’m sure it has to do with your bodies way of handling inflammation but I’ve never done a deep dive.