8 year old has been sleeping on his back for over an hour his resting heart rate at wrist is 108. Hes on two different sedatives. Is his BPM a litle high?

Normal. As you can see from the chart, 108 beats/min is in the normal range for an 8 year old. If the sedatives lowered the heart rate, the body may compensate to maintain normal.
The heart rate is . Borderline high for a child who is sleeping. Normal resting heart rate for an 8 yr old is 70-110 bpm. The more important question is why is he on two sedatives? That seems like a bad idea. Is this being managed by a doctor? If not, please consult one right away or stop giving the medications.