Bed explosion strength varies with orientation

The orientation of beds in the Nether has an effect on the strength of the explosion resulting from attempted usage.

In the attached images, a bed was lain in each of four possible orientations on both netherrack and nether bricks. As sunflowers will point to the Nether's East, they are included in each frame for reference.
The netherrack test was followed by a secondary set of bed explosions of the same orientations, which shows a consistency.

Results (direction is that faced by head of bed):

East: small explosion, significantly less fires started. Deals only 1 health point of damage.

West: large explosion

North & South: small explosions