Here's an easy way to tell if you've had mania. Since your own judgement is impaired, ask one of your friends.

I consider myself to have very mild episodes, but my friends usually comment on it.
- They tend to be surprised when I start waking up early in the morning or staying up until morning
- They tend to comment on my speech. I remember one particular example where I was telling my friend a story; he was nodding his head while I was talking, but when I finished, he said "I have no idea what you just said." (My speech tends to jump from topic to topic and contain a lot of minor, irrelevant details which only seem to fascinate me.
- They'll joke and say I have ADHD or PMS (I'm a guy). Because I get really pissy and easily distracted.

If you go through a period of high energy where your behavior changes enough for those close to you to notice, then there's a good chance you've had a hypomanic or manic episode.