Keep waking up in the middle of the night.

I don't know why I didn't feel depressed for the past two days. I went from having suicidal thoughts all the time and feeling glum to feeling perfectly fine.

Is it possible for a depressive episode to last only 5 days? I don't get it. But I know I was depressed with the awful feelings, excessive sleep, and suicidal thoughts. I also always feel "pressure"the in my head when depressed, and I had that too. I'm so confused.