When sleeping in bed, the person is lifted a few blocks up, and is floating in mid-air.
To reproduce:
1. Place a bed
2. Place blocks around you as markers (for example 3 layers of green, yellow, red wool/stained clay)
3. When you sleep in bed (when it's nighttime), you will float 1-2 blocks above the bed (maybe more).
Confirmed, gave me x-ray vision due to my low roof and it putting me inside of it