This item belongs to the very small class of
magical items that would be very good
In Real Life, but are very bad in
NetHack (others include the
amulet of change and
potions of hallucination). When the
amulet is first put on, you will fall
asleep in 1 to 100 turns,
awakening 1 to 20 turns later or when disturbed. The cycle then repeats.
Considering that monsters get free hits on you while you're asleep or unconscious, this amulet is definitely hazardous to your health. Furthermore, it's usually generated cursed, which doesn't help matters any. The amulet has an amusing tendency to put you to sleep as you are about to remove it.