The same thing happened to me. My thoughts: "I don't understand why this bed is shaking. Does this Japanese bed have some sort of massage mode that got triggere

The same thing happened to me. My thoughts: "I don't understand why this bed is shaking. Does this Japanese bed have some sort of massage mode that got triggered somehow? Silly me, if it had a massage mode, I would have noticed electronics somewhere. The people downstairs must be doing something. Ok, back to sleep."