sleepyhead (n.)

• dawdler
• drone
• goldbrick
• goof-off
• laggard
• lie-abed
• lingerer
• loiterer
• plodder
• procrastinator
• sleeper
• sleepwalker
• slowpoke
• slug
• slugabed
• sluggard
• snail
• somnambulist
• somniloquist
• stick-in-the-mud
• tortoise