there is an option if the goal is to synch kittehs for breeding, albeit it does cost, the catnap and catnap 0 vitamins will make them sleep either from the point they are at or take them down to 0, whichever you need. Unfortunately Winter is right, I dont think there will be a no cost option anytime soon, but the catnap vitamins are only 100L which compared to the other vitamins and things we get for them is nothing. You will need one per cat you are trying to synch unless you catch one at the moment they start their nap, then give their partner the catnap 0.
Good luck
Kitty Cats Are Like Potato Chips, You Can Never Have Just One 
