The Elaysian physique and neural motor cortex was adapted to cope with a low gravity; on their homeworld, they were virtually able to "fly". When exposed to Earth-normal gravity environments, they needed physical support to function. The type of support varied but included wearing an external skeleton with integrated servomotors which helped by supporting the person's own skeleton, although this only functioned for short periods of time. For longer-term physical support, other forms of support were needed, like a wheelchair or an anti-grav unit.
A medical treatment was developed by DoctorJulian Bashir, based on earlier neuromuscular adaptation research by Nathaniel Teros. By elevating the neural output to the brain's motor cortex via neural analeptic transmitters, he improved his theory and made this treatment possible. The drawback of this treatment was that if started, no exposure to low gravity environments was advised, because this would confuse the person's body and motor cortex. When complete, the person could move naturally in Earth-normal gravity, just as most typical humanoids did. The results of the treatment were irreversible.
In the first draft script of "Melora", the name of this species was spelt "Elayshan".
Because the character of Melora was to feature as the main Elaysian and was to be involved in a romantic relationship that had to be believable for the other partner (namely, Dr. Bashir), the producers wanted the Elaysians to have a strange-looking forehead but no extensive make-up below the eyes, the producers issuing an instruction for Make-Up Supervisor Michael Westmore to keep Melora beautiful, although she was an alien. The make-up department designed and created an enhanced appliance that ran from the ridge of the nose and stopped at the forehead. Each of the Elaysians were also given a receded hairline, to allow for their forehead appliance. (Star Trek: Aliens & Artifacts, p. 152; Michael Westmore's Aliens: Season 2, DS9 Season 2 DVD special features)
In the Pocket TNGnovelsGemworld, Book One and Gemworld, Book Two, Elaysians were featured along with several other species from the same planet. The Elaysians (together with the Alpusta, Gendelli, and Yiltern, but not the Frills, who were native to the planet) had been transplanted from a different dimension by the Lipul, oldest of the planet's inhabitants. The multiple species had developed technology to prevent their homeworld from expiring, without which it would have self-destructed long ago.