Why would i be put on an antipsychotic for my mania?

Hello everyone.I went to see my psychiatrist yesterday in Glasgow.For over a month i felt high and elated. I wrote down how i had been feeling and showed it to my pdoc.She said it sounded alot like a manic episode. She put me on 2mg of Risperidone for the mania but i am a liitle confused.I don't have any psychotic symptoms so why would i be put on an anti-psychotic for my mania?Thanks for your input.