So, what's the point? Is that mean "Don't keep them unsolved untill midnight" or "Just put them off tomorrow" ? 

Generally serious matters keep me up at night so I solve them in the middle of the night...

It is true if you are sleepy، but in generally it depends on your personality,  for me i am very active in night

It depends on the kind of trouble i get in.Sometimes,i choose the way ignoring it but also,usually it'll be unwise if i do not do anything , just sleep and resolve it in the next morning.

**"Just put them off until  tomorrow"