Reverie

Reverie is the elven state of meditation, which has certain sleep-like effects. During the meditation, sometimes referred to as a "trance," the elf conducts a series of mental exercises which refresh the elf's body and mind. During this meditation an elf is fully aware of the outside world, though breaking meditation in response to external events has an effect on the elf similar to disturbing the sleep of any other humanoid.

Elves do not actually require sleep as such, but rest in reverie for generally half as much time as the other humanoids sleep.

Elves are capable of sleep, but only when they are severely ill or wounded.