Does melatonin cause drowsiness

It does for me. I read that higher doses can make you feel groggy, so I stopped taking the 3mg dose and switched to the 300 mcg, which is the smallest dose tablet I could find. Taking between one to three of the smaller dose tablets seems to work better for me. I just got eight solid hours of sleep, after working the overnight shift, and feel pretty refreshed with no grogginess or headache.