Insomnia is a fake idea invented to promote the industrial work cycle. If you go to sleep when you're so tired, as opposed to when the societal clock says you should, you won't have any trouble sleeping.
Great PMA, but you're absolutely wrong.
I did that last night, got tired and went to bed around 10pm. And then I woke up at 1am. Now that it's approaching 6, I'm getting tired. But this happens to me occasionally and I know from past experience that my two options are:
1) Go back to bed at around 7, wake up at 8 or 9, and feel awful all day
2) Power through, and feel awful all day.
Maybe I'll be tired enough tonight that I'll catch up on this morning's loss. But given past experience, I'll probably get 2-4 hours of sleep a night for the next week. When I say "wake up" I mean that I'm alert and can't get sleepy -- I can stay in bed and be bored for hours, and sleep won't come no matter how tired I feel.