The notes say that the night monster may be a reference to a demon.
לילית liyliyth (in Hebrew)
= "night creatures" (NIV, NKJV, NLT)
= "screech owl" (KJV)
= "night bird" (ESV)
= "night monster" (NASB)
= "night hag" (RSV)
= "the lilith" (NAB)
= "the lamia" (DRB)
[NB: lamia means "witch" or "sorceress"]
Thanks, Mark for the etymology.
You can tell I use the NASB.