Would you mind sharing exactly which of your emotions you are trying to suppress? Is there something in particular like anger, sadness, etc
Are you just trying to be less hyper, as you mentioned? So, you have too much energy?
I have bipolar disorder and for me too much energy means that I might be in hypomania or mania so I have to take a heavy duty med, Zyprex, to help balance myself when I have too much energy.
For people with bipolar disorder, for example, psychiatrist believe it's a bad idea to give something like an antidepressant for instance because it can trigger mania, especially if one's not on a mood stabilizer.
if this is too personal or you'd rather not say I understand, then don't say anything. But understanding better what you're trying to accomplish, you'll get better suggestions.