That's kind of interesting, but think about it — what difference will it make? Your Sim is going to be asleep most of that bonus 12 hours anyway. It's not like your Sim would be in any kind of shape to do sparring or tomb exploring in that time period — especially if you're saying they need to be very tired for this trick to fire to begin with. So, they're not going to be good for much of anything before you'd put them bed.