Possible Clues:

• Dreaming sleep phase, briefly
• Letters for deep sleep
• Band with the #1 album 'Monster'
• Sleep stage abbr.
• 'Green' group
• Polysomnogram letters
• Band with the 1993 hit 'Man on the Moon'
• Band with the album ''
• Matter, to Marc Antony
• Band with the multiplatinum albums 'Out of Time' and 'Monster'