I was always wondering about this, so thanks for starting the Topic.

By now I am diagnosed as bipolar NOS and my t hesitated with this diagnosis for a Long time because she said she couldn't SEE my hypo.

I am a pretty controlled Person and can hide stuff from others pretty well. When hypo I start talking more than usual but I tell funny stories so noone ever complained. I start moving restlessly which has been pointed out to me a few times. I can become very aggressive and sensitive or very happy (right now on the aggressive side). I can also become very focused or unable to Focus. My thoughts start racing. Usually I do a few Projects at a time and finish nothing. I start to have increased Appetite or None at all (right now None). I come up with creative Projects and lose interest in work or become obsessed with it. I won't sleep much anymore but as I am single noone notices. I tend to put myself in angerous situations, have Trouble listening, will do more drugs and drinking. Alone at home I run and Dance and sing and one sure sign for me to be going hypo is changing languages. I am German and all of a sudden I will start talking to myself in English, Spanish, Portuguese and a few more.

Anyway, many of These behaviours I seem to be keeping to myself and not let them Show too much. Sometimes People tell me that I seem to be moving around a lot or very emotional about my ideas. But that is it. Noone can really see the whirlwind inside.