Some I have to wake either from too long a nap or due to lack of sleeping well at night (per parents request), just depends on the kid. I have one who would sleep for like 5 hours if I let her and have had parents ask me to shorten naps due to lack of will during bedtime. I don't mind, the only thing I won't do is keep a child from sleeping at all, or allow a child to make noise and distrupt the others.