While the term “neurasthenia” has a highly variable history and is no longer in use, it was generally used to refer to a condition of nervous weakness or exhaustion. Samael Aun Weor provides an interesting description:
"The world is full of neurasthenic persons. The neurasthenic type is a faultfinder, irritable, and intolerable. There are many causes of neurasthenia: impatience, anger, egotism, arrogance, etc.
There is a mediator between the Spirit and the body: the nervous system. Take care of your nervous system. When your nervous system is irritated by something that is exhausting you, it is better to flee from it. Work intensely but with moderation; remember that excessive work produces fatigue. If you do not pay attention to fatigue, if you continue with excessive work, then fatigue is replaced with stress. When stress turns morbid, it becomes neurasthenia. It is necessary to alternate work with pleasant rest so as to avoid the danger of falling into neurasthenia." —Samael Aun Weor, Introduction to Gnosis