"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.

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

Vibrant and Varied.

Different hair colours have origins to the Dark Days, when the first of their kind awoke to the blooming, nascent Erellurn. See Tuath Phenotypes.

Hair being a prominent source of identity and importance to their people has led to particular fascination with harlequinism. Particularly because one of their chief ancient heroes, Zhaine and his father, had hair in a near-perfect split of two tones.

Even the Aelhir word for chimerism has a double meaning. Elero/Elerae. Both 'eclipse' as in partial obscurity or lunar phases and 'split/mixed fate'.

^(v.)Bir elero'le - "I have eclipse(d hair)."