Reverie

Reverie, or trance, was the elven state of meditation, which had certain sleep-like effects.

Description
During this state of meditation, elves conducted a series of mental exercises that refreshed the their bodies and minds. During this meditation, elves were aware of the outside world, though breaking meditation in response to external events had an effect similar to disturbing the sleep of any other humanoid.

Elves could use any comfortable surface to sit or lie down on to undergo reverie, though some avoided using human beds.

Sleep
Though elves were highly resistant, or even immune, to magical sleep effects and spells, this did not mean that they were physically unable to sleep. Elves were sometimes able to sleep if they desired, though they almost always rested in a state of reverie, which took half the time for the same benefits of sleep, and also acted as a memory tool. As such, elves very rarely slept, and usually only did so when they were severely ill, wounded, or exhausted. It was thought that the ability for elves to go into reverie, instead of sleep, was the explanation as to why they could shrug off magical sleep-like effects.

Though most types of elves did not sleep in the majority of scenarios, some types slept more regularly. Drow were one such race, and generally slept far more often than their kin on the surface. Some drow slept, whilst others entered reverie, in order to gain typical rest. When drow were exhausted after tiresome events such as Open Days, they would close their shops or residences and acquire sleep. Even major Houses would close and have an already-rested set of guards to look over the House members while they slept. Drow were also known to seek out stalactites that had had the silence spell cast upon them, and slept inside their hollowed insides when they required rest. However, not all drow slept, and many preferred reverie. With every passing century, less drow were able to fade into reverie, and instead needed actual sleep in order to acquire gainful rest.

Several individual elves did not undergo reverie, or were known to have fallen into a state of sleep:
 * Galaeron Nihmedu, a half moon/half wood elf, lost his ability to undergo reverie after excessively using the Shadow Weave
 * Gromph Baenre, the powerful drow archmage of Menzoberranzan, was unable to enter reverie, even in spite of his high level of discipline. He had been able to slip into reverie at a much younger age, however.
 * Filsaelene Merwyst, a sun elf who was so exhausted and emotionally frail that she fell into a state of sleep