For the past year or so I've been adding 2 tsp of apple cider vinegar to my water before I go to bed. Drink as much as I feel I need to top off my hydration and finish the rest the next day. I sleep well nearly every time I do this after years of less than great sleep. I haven't tracked rest vs riding days and the vinegar but if I think about it, I make more effort to drink it on those rest days.

This came from a book originating in the 1950s of traditional Vermont farm practices, beliefs and superstitions. Far, far from any approved source. But, for me, the single best sleep improvement I've tried. I just came back from the week long Cycle Oregon. Day two I discovered the packages of Italian dressing had the first ingredient vinegar. Made a point of consuming a salad and that package every day. Best sleep yet in that noisy and not always ideally level tent.