slugabed \SLUHG-uh-bed\ (noun) - One who stays in bed until a late hour; a sluggard.

""Don't you Auntie me, you slugabed! There's toads to be buried and stoops to be washed. Why are you never around when it's time for chores?" -- Michael Swanwick, 'King Dragon'

Slugabed is from slug, "sluggard" + abed, "in bed."