There are some nights mine decide that nighttime is playtime. Some nights it is a quick romp and others it will last for hours. On the nights it lasts for hours if the next day is a weekend day I won't let them sleep. Everytime they try to settle down for a good nap I wake them up and make them play or take them outside for some sunshine or something in that order. I find then I get a wonderfully quiet night that night...