I found more proof ,while playing just before night the villagers I captured slide on bed and went through wall and were sleeping in air ,so at night time the teleport and sleeps in air ,and i think that would make them vulnerable to mobs ,so pls resolve this problem as soon as possible 

Those were the only thing I say moving really fast and rest went away ,the villagers in the photos stayed there

Regards 

Pls consults photos and pls zoom in for better view