When our children sleeps that's a great time for their minds to process new things they will remember. And its great to know that they will remember more about you and about themselves.
It's a good idea to sleep with your child sometimes, like when he or she is taking naps. Kids are busy all day and its good to differentiate quiet time. They can appreciate a good nap and for you to be there with them humming a lullaby or stroking their hair even is a good way for them to develop a sense of security and safeness with you.