Sleeping platforms differ from thrones because they tend to be positioned away from doors & have dimensions proportional to the height of elite Mayan males (who tended to be taller than the general population). Sleeping platforms have sub-spring beams positioned near the foot of the bed where curtains could be hung for privacy and possibly protection against insects. Sleeping platforms tend to contact two or three walls, and may have a raised pillow-like area he calls a "backscreens".
Peter Harrison, The Central Acropolis, Tikal, Guatemala: A Preliminary Study of the Functions of its Structural Components during the Late Classic Period, 1970. Unpublished PhD dissertation, University of Pennsylvania, p. 179