(1) Same as the definition forbody bag. All but one of the examples given on this 'body-bag' page illustrate the 'corpse envelope' meaning, not the 'sleeping bag' meaning given above.
(2) Only one example sentence here illustrates "n., A bag to sleep in." And that would be the sentence from Fat Is A Fantasist Issue: ' Mrs Cole could get her fourteen hours sleep in a seaweed body-bag . . . '