I think that it is not very convenient to play at night, the neurons do not work very well, the tiredness of the body and sleep play very against, the best thing would be in the morning with a good breakfast and bath and to play it has been said
Man, this is complicated. In the vast majority of people, really, at dawn, the brain does not work well, but for some, it is the best active time, everything will vary according to the person's habits.
Truthfully it depends on your observation of the tournament structure, its duration, and how able you are to last all the way to final table. One particular MTT I play starts at 8:15 PM PST (I live in SoCal) so I have a bit an advantage compared to the East Coast and it often ends a few minutes away from midnight (again PST, so I am looking at 3 to 3 1/2 hours). I have managed to score myself $1000 from that MTT twice and I often get close to final table.