Could zocor (simvastatin) cause night leg cramps?

Possibly: All statin-type medications, of which zocor (simvastatin) is included, can cause muscle breakdown resulting in muscle pain ranging from mild fatigue to severe pain and weakness. It would be unusual for zocor (simvastatin) to cause pain limited to nighttime only.

Maybe: All statins including zocor (simvastatin) can cause muscle pains, usually proximal muscles such as thighs or arms, and usually bilaterally. If you have this, check your ck blood test with your primary care doctor to rule out a more serious complication and try to stop it to see if the symptoms disappear - they always do in case of statin associated muscle pain within 1-2 weeks of stopping the medication.