Always carry as much fuel as you can (lots of alternate fields closed at night), check for carb. ice more frequently, more thorough preflight check than usual, then the engine won't stop anyway. And if it does, tough. (That's what I tell my students anyway). I don't think there's any reason the engine should stop more readily at night and if you take care of the above you've covered the main reasons before you start.
To my mind the sheer pleasure of night flying far outweighs any potential risk.
Cheers DB6
[This message has been edited by DB6 (edited 20 November 2000).]