I often get mood swings going from happiness to sadness but i never get hypo unless i'm drunk. is there a reason for this?

Could be serious: Mood swings that you describe can be found in a very serious psychiatric problem called bipolar disorder, previously manic-depression. Alcohol is a very bad thing in people with bipolar disorder (or its milder brother cyclothymia), treating some of the symptoms while ultimately making them worse later. Please see a mental health professional and stay away from alcohol while you are doing that.

Alcohol Disinhibits: I am assuming when you say "hypo" that you might mean hypomanic. If so, a possible explanation for having only this more extreme energized mood when you are intoxicated is that alcohol is disinhibiting and shuts down parts of the pre-frontal cortex that control behavior. And, hypomania does the same thing by a different mechanism so the state of being intoxicated facilitates being hypomanic.