Running in the day is better by far, but sometimes other commitments dictate that my run'll be late.
I'd rather run late at night than not at all.
BUT,
Any decent session raises the metabolic rate sufficiently for you to need a few hours calming down time before you'll be able to sleep soundly.
I was out late last night.
Black night, no moon.
Ran on a cyclepath, 6 mile out, 6 mile back; comfortably hard tempo run.
Crashed into a bollard once - Ow!
Stumbled on detritus many times - no twisted ankles, thank goodness.
Nearly collided with a man walking along miles from anywhere. We saw each other when about a metre apart and both screeched and recoiled in panic and terror - would have been funny to see, but I don't want to repeat it.
This session turned a mundane run into a mini adventure, but it'll be a while before i do it again.