When you get into a bed facing from the foot towards the head (i.e. when getting in you turn around), you end up looking at chunks that are not rendered.
MC-63070 - when viewing chunks outside the normal frustum either by their method (F5, high FOV) or this one (bed) they won't render. Fixing one should fix the other.
Steps to easily reproduce
1. Build a wall
2. Stand on one side of the wall, facing away, inside a different chunk
3. Put down a bed in front of you
4. Get in the bed
5. See un-rendered chunks