"The Elven folk, with hearts so light,
Their laughter rings through starlit night.
And mark their crown, a wondrous sight,
With hair that shimmers like spun moonlight!" - Darling the Bard

Elven hair is significantly connected to the nervous system and part of elven physiology.

Cutting the hair is a tremendous insult and damages an elf's ability to sense aether fluctuations until it regrows. 

Because of its connection to their nervous system, styling of the hair is also of some significance. Although most styles are purely aesthetic, tying the hair up and high such as with the famous unicorn-tail has the effect of increasing attention and elevating sharper focus. Most elves would explain that such a style makes them feel activated, in a manner-of-speaking.

Most other species associate the unicorn-tail with Elven warhosts due to how often the style is worn in combat.

Likewise, looser styles are regarded by elves to be relaxing.