How to stay awake

I've never played in a tournament that lasted this long, but if I did, it wouldn't be at night because I know I'll fall asleep. Oh, and coffee doesn't help me at all.

Slipping well before and than a good strong and black coffee

Take a walk outside or a cold shower in the break to stay focus

These days I like to know the expected finish times of any mtts I am planning to play then set out a schedule with a few cheaper fill in hypers to replace early exits. The old proper planning prevents poor performance. Being super alert is so important for that last hour.

Maybe drinking coffee or energy drinks can help, but I usually don't do this, as I avoid to play while I'm very tired and as don't like coffee.

Anyway, hearing a good and and happily song also may help you, as the intense loud can make your mind be more active.

Other thing I can recommend is to turn your lights on (if you are playing at night; artificial lights has tons of lumens and can destroy your sleep routine, so you can use this in favor to accomplish your objective) or be sure that your room has light enough to don't make you brain think you are awake at the wrong time of the day and start to send melatonin to your body (if you are at daylight).

And you can also take a good shower (specially if it is with cold water), of course!

Tea helps, or you are distracted by a YouTube or humorous video