He just may be a talker. Its more of unspayed females who are annoying when they go into heat.
Boys don't go into heat of course, and it is possible he is seeking a mate, but i'd put it more towards what catlover2 suggested for trying to tire him out before bed.
Of course it's always great to see people getting their cats fixed
and maybe once he is neutered he might calm down and will quiet down a bit.