Can sleeping on your side make pisiformis syndrome worse or even cause it? thanks for taking the time to answer!

Doubtful: Very doubtful that sleeping on the side would cause piriformis syndrome. I wouldn't worry about that as being a causative or worsening factor. There is some controversy about piriformis syndrome (some docs don't really believe in it), but in most cases conservative treatment can help, so see a physician if symptoms persist.

Theoretically possib: When u lean on the bone and nerve structures. Continue taking the ibuprofen. Warm packs and ace wrap application may help. Take care! http://www.healthline.com/human-body-maps/pisiform-bone. http://www.medicinenet.com/wrist_pain/symptoms.htm.