I have to agree with Judy. I have one naproom and all the children fall asleep and wake up within 1/2 hour of each other because they know our routines and they know I have clear expectations from them. I sit right here in the room with them and shush them if necessary and tell them that I'm taking care of them until they are sound asleep. Some days they ask for a few songs. It works.

When I have a new baby join I sleep them in the next room so I can sit with them to help them learn that naptime means laying down and sleeping with no other options. By training them this way for a couple of months I am rewarded by having them mix in as quickly as possible with the others.

Blackout curtains help a lot too!