I was about to ask this question too. I did two weeks gluten-free and felt fantastic. I was getting up early. Then I ate wheat for a week to get some blood tests. I was constantly sleeping, but that was with wheat. Now I've been gluten-free again for maybe 5 days and I'm still sleeping all the time. How do I know what is from accidental gluten and what is from healing?
The weird thing is, I'm so tired in the morning, and then I'm a total night owl after about 4-5pm. This is just the opposite of how I used to be.
I had a similar experience. I think it takes time for the gluten (or the effects of the gluten) to work its way out of your system. I went gluten-free for about 6 weeks (after a long-term low gluten diet) and was feeling much better, including sleeping better and waking up earlier. Then I went back on gluten for a week and felt miserable. I'm at about 5 weeks now and just starting to feel better. It seems to have taken longer this second time to start seeing improvements.
I also saw a change in my daily rhythm. I'd been an extreme morning person all of my life. When I got sick a few years ago, I noticed that I was sleepy all day and didn't wake up until about 3-4:00 pm. The only time of day I felt awake was from about 4-10:00 pm --- pretty much the exact opposite of my normal cycle. I think it has something to do with our cortisol production being screwed up from having a long-term chronic disease. I was definitely waking up earlier and more refreshed when I had been gluten-free for 6 weeks. I'm hoping I get back to that point again soon!