Every bodies chemistry and reactions to meds are different so just trial and error. It may or may not have caused me sleep issues as I had already been suffering with those issues due to this illness. IIRC it did cause an interesting dream life for a time. Now I have no problems taking it at night. Also, I didn't have the sensitivity to it that others reported, started out cautiously at 1.5 mg and quickly went up to 3 then 4.5 mg