I won't tell since when I started masturbating.. but w/e
Lately it seems I just become more AWAKE after ejaculating. Maybe because i've been physically / mentally active and thus it removes the tiredness, I don't know. in the past it did use to make me tired.

I'm not sure how jerking off but not ejaculating would work, having sexual urges non-stop till you fall asleep seems more annoying for me, but who knows

However I would consider it a no-no if you become really tired after it, it would probably make you go into such a deep-sleep that it screws up your recall / lucidity, I don't know, just a guess.