Villagers occasionally look around while sleeping

The Bug:

While asleep in their beds, villagers sometimes move their heads to the side as if looking around. Sometimes tilting their head directly at the player. The behavior is inconsistent, but it usually happens if there is an entity near by for them to look at, especially if they're moving.

It takes a while to trigger sometimes, but it definitely happens. I assume the correct behavior is lying still. 

Screenshots: