A quick search of Internet sites produced the following:
1. Narcolepsy is a chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden attacks of sleep.
2. What is the root cause of narcolepsy?
Many cases of narcolepsy are thought to be caused by a lack of a brain chemical called hypocretin (also known as orexin), which regulates sleep. The deficiency is thought to be the result of the immune system mistakenly attacking parts of the brain that produce hypocretin.
Astrologically,
Sleep disorders and/or the unconscious comatised state see the influence of Neptune,
anything 'chronic' of nature sees a signature of Saturn,
the (mal)functioning of the immune system usually involves harsh Saturn-Neptune aspects.
Saturn represents the control and responsibility over 'self'. It's the manifested limitations of the physical body ...its outer skin that protects against invasion of that which is non-personal to, and not good for it.
Neptune in harsh aspect can have 'a weakening' effect upon the physical body .
Astrologically, it rules the complete (endocrine) glandular system, with each individual gland ruled by a specific planet.
Saturn rules Capricorn at I.C., and is the traditional ruler of Aquarius on 5th cusp.
Neptune is modern ruler of Pisces on the 6th house cusp (physical ailments).
There is a Sun in Aquarius square Saturn. Paternal issues?
Saturn is semi-square (predisposition to manifested disorders) Neptune.
Mars conjoins but its energy is inhibited by Saturn that is, itself, weakened by Neptune. The emotional outlet of Scorpio is contained.
Mars rules Aries ...the workings of the brain.
Planetary energy that should be used externally for one's self works 'inwards'.
Discover the meaning behind the planetary symbolism, as well as the influence of other planets in their specific equations, and an answer for narcolepsy, other than purely medically scientific, could well be found ... and cured (positive Neptune).