What I remove for elves is their immunity to sleep. The trance is something they can do, a learned technique that could, actually, be learned by non-elves as well. The natural rest of an elf is sleeping, like everybody else, from puppies to great wyrms.
However, the elves have very poor memories, and no real notion of time. They live in the present, the past is all blurry, and the future is just idle speculations. The discovery of the trance technique allowed them to overcome these racial limitations, by refreshing their memories in their mind; allowing them to build their own civilizations.
Elves need to trance at least once per month, otherwise they begin to lose memories, and eventually, levels above 1. Then they lose Int points until they reach the animal-like score of 2.
Elven education is so very lengthy because young elves need to be tamed as much as they need to be taught. Only once they master the trance can they really be educated.