Make sure he had a really big and fluffy stuffed animal to hug. Keep at least one and maybe more nightlights on all night, and the room light if he needs it. If he feels that the baby is taking his place and he is being pushed aside, he may be terribly sad. Perhaps you should let him sleep in a sleeping bag on the floor near your bed, although it would still be the baby beside Mom. This would be a bad time to train him from sleeping with you. Perhaps you should have both in your bed for a while, You don't want him to think the baby is now taking his place.
at 4:42 PM on Mar. 4, 2009