It's prescribed for social anxiety and stage fright as a secondary use, but like the poster above said it won't do anything for your mind. Just reduces the unpleasant physical symptoms of anxiety.
Taken in higher doses (100mg+), it tends to have a sedating effect, but how sedating appears to vary from person to person, and the effect may not last long.
Enough propranolol can render you unconscious, but taking high levels of propranolol can damage your kidneys if done repeatedly.