The ornamental design for sleeping garment, as shown and described.
FIG. 1 is a front view of a sleeping garment showing my new design;
FIG. 2 is a back view thereof; and,
FIG. 3 is a front view with sleeves zippered across the front thereof.
The single broken lines in the drawings depict portions of the sleeping garment that form no part of the claimed design. The dotted lines at the wrists of the garment depict stitching on the garment, and form no part of the claimed design. All of the seams on the garment have no appreciable thickness. Additionally, the diagonal lines across the front of the sleeping garment depict zipper tracks for mating with the zipper tracks along the length of the sleeves, and have no appreciable thickness.