Can someone confirm this droop is the circadian rhythm?

After looking at your diary, I would stop with the hydrogen peroxide(!) and I would suggest never giving your plants distilled water. Distilled water has nothing in it, such as dissolved salts, calcium etc. and when applying it to your plants can actually "suck" these dissolved salts out of your plants cells via osmosis. If you are concerned with chlorine etc. in your tap water, just fill a bucket or three with tap water and let them stand for a couple of days before using the water. Leaving the buckets of water to stand will cause most of the chlorine and any other chemicals to evaporate, leaving you with well balanced and clean/chemical free water. Your babies will pick up in a few days and continue growing normally. If you are really keen, you could give them some sort of seaweed extract/tonic, as this will really pick them up quickly and is also good to use periodically as a soil stimulant. If you live where you get pretty warm in summer or quite cold in winter, using the seaweed tonic a day or two before the extreme weather hits, will help your plants battle through those temperature nightmares. Hope this helps... Organoman.