We play whenever they want to. Lately we have been supplementing / replacing playtime with going outside for walks and grooming. The grooming isn't necessary really because they are 99.9% indoor and DSH's, but it is yet another way to spend time and stimulate them. We try to tire them out before bed, and then hit 'em up with some turkey as a snack. Tired cats + triptophan from turkey = good sleep for us. Also, we are being more creative with their toys............it is amazing how long a hair scruchie thing can hold their attention.