When you sleep under certain blocks, you sink into the bed

When you sleep in a bed with a block two blocks above, you can sink into the bed.

This only works in certain blocks listed below:

• Lantern
• Bell
• Heads / Skulls (Player, Skeleton, Wither Skeleton, Creeper, Zombie, Dragon)
• Grindstone
• Hopper
• Another bed (see MC-150447)