Hi
@Mary -- Interesting to read your update. My first thought was it may be that your "sweet spot" (dosage) may be fairly minimal. If so, I cant' help but wonder if a slightly lower dose might get you improved sleep without the extra tiredness during the day.
Also, a friend of mine once started taking an effective pain relief medication, and immediately started sleeping a LOT. When she asked the doctor about it, he said that it was quite common for people who've been sleep deprived to go through a period of time (around a month if I remember correctly) of a lot of extra sleeping to make up the sleep deficit they'd built up over time.
I wonder if it's possible the improved sleep has shifted you into some sort of new cycle, and that the extra tiredness during the day may not necessarily mean it's a bad thing. Just doing a little thinking and speculating out loud. Life and health is (almost) always a mystery!