I know that medications can have an affect on sleep but this situation kind of baffles me. 

I'd pulled some muscles in my lower back and have been having muscle spasms for about a week.  For timeline purposes it started last Wednesday night.  Normally i sleep okay and my ZQ averages 100. Average for Deep is 2h 11m, and average for REM is 2h 10m.  During this last week my sleep hasn't really been affected (only how long it takes me to get in and out of bed).

Becasue of the injury I was expecting to see some higher Deep Sleep cycles which would indicate healing which I did on a couple of occassions.  On one night 40% of my sleep cycle was in Deep. The other nights were between 29% and 40%.

After 5 days (Tuesday) I went to see a doctor who put me on the following - Soma (muscle relaxant, Valium, and Hydrocodone for pain).  I took one dose in the evening on Tuesday and when I got up on Wednesday, I'd slept about 7h 15m, and 52% of that was in light sleep, 19% in deep, and 28% in REM.   

After taking 3 full doses on Wednesday, when I got up on Thursday (this morning), I'd slept 10h11m and showed that I'd been awake about 6 minutes during the night and only 8% (48 minutes)  of that time was in Deep with the majority of the time being in Light Sleep (50%). ZQ was 108 which for 10 hours for me is low.  Contrast that with 7h 4m on Monday night and a ZQ of 101 and a Deep Sleep of 40% (2h 55m).

I'd really expected to see my Deep sleep scores go up while taking this type of medication, not drop.  Just wondering if anyone might know something about pharmacology and why this might be the case or if it's an anamoly.  I understand that long term use of certain medications, even those prescribed for sleep, can cause disruptions in sleep. However, I've only taken these for 2 days. No allergies either and I've taken two of these medications before, one for a root canal, and the other was more than 10 years ago with no difficulties.

Note, not looking for medical advice, just curious if my assumption about these medications causing someone to sleep more deeply is wrong or if they have the opposite effect on sleep cycles then what I'd think.

Thanks.