I'm a medical student too. The muscle relaxant effect only lasts for a few hours. I'm mainly using it for the anxiolytic effects which last the rest of the day. Drowsiness only happened if I took the high dose at night thus affecting sleep quality. I didn't ask a doctor. However Baclofen is also used for other off label purposes such as alcoholism treatment and cocaine dependence. So it does have powerful psychoactive effects due to it being a potent GABA-B agonist. Incidentally, the working theory of stutter happens to be due to too much dopamine in the basal ganglia. GABA antagonizes dopamine.