Sleep prevented by nearby mobs even in Peaceful mode.

Put the summary of the bug you're having here

What I expected to happen was...:
When I place down a bed at the beginning of the night cycle before mobs have a chance to spawn, I expect to sleep. 

What actually happened was...:
Several times I was unable to sleep even in Peaceful mode. I tried to place the bed in a different spot and keep getting the same message. I have tried going into spectate mode to see if there are mobs underneath me in normal mode but it does it even when there are none withing a chunk or more.

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. It happens very frequently in both normal and peaceful modes. Being able to sleep is intermittent.
3. ...