It supports the movement downward.
His head hangs.
His neck is no longer being actively held in a normal elevated position.
That does not necessarily mean the posture is medically ideal.
But it may help explain why Mochi repeatedly returns to it.
He seems able to relax there in a way he struggles to do elsewhere.
Staff Notice That He Rarely Changes Position Once He Falls Asleep
A younger, comfortable dog may reposition repeatedly during the night.
Stretch.
Curl.
Roll onto the opposite side.
Move the head.
Mochi does very little of that.
Once he finds the edge, he stays there.
Sometimes for hours.
The lack of movement is not necessarily a sign that he is extraordinarily comfortable.
For a dog with painful joints and weak limbs, remaining in one imperfect position may simply be easier than getting out of it.
The Strange Posture Creates a New Problem
Mochi does not stay perfectly still on the mattress.
Little by little, his body slides.
The movement is almost impossible to notice from moment to moment.
But over time, his shoulders creep closer to the edge.
His head descends.
His nose gets closer to the floor.
Eventually, his center of gravity shifts enough that his body seems ready to follow his head.
That Is When Mochi Wakes
His eyes suddenly open.
His front paws tense.
For a second, his body hangs awkwardly between the mattress and the floor.
Then Mochi tries to pull himself backward.
It is not an easy movement.
His front legs shake.
His shoulders rise.
He gains perhaps two or three inches.
Then he stops.
He Doesn't Move to the Middle of the Bed
That is the detail staff cannot ignore.
Mochi has just awakened because he was sliding too far.
He has corrected the immediate problem.