I'm the same way if I work out after work or in the eve. Since you have insomnia, try working out first thing in the AM. I get up between 4 and 5 AM, pop a fat burner and hit the gym. I found I get a much better workout, and can actually fall asleep at night easier.
Give it a shot, it's tough at first, but, after a few weeks it'll feel like you've been doing it all your life...