pocohantas:
First, you should be happy your woman (women) loves to lay on your chest. It shows you do not have a life-span-depreciating body odour. Even if you do; they love you enough to overlook it

Anyway, possible reasons;
-It gives a sense of security with his arms around her. Like she is your Lois Lane.

-Intimacy. I think there is a biological name for that attractive smell that men have. It has this allure.

-To hear the thump of his heartbeat. When having a deep conversation, she can tell a lot about his stand from his heartbeat.

Ultimately, I have met very few women that can sleep in that position all night. It is just for a goodnight bonding, when better sleep sets in, everybody go find their level.

Bear with us, we know it is selfish, but some selfishness in relationships turns out ego-massaging to the other party. That is why you are here asking us this question, you are not irritated_ you like it.