Neurosis is a group of diseases characterized by functional disorders in which the patient maintains a critical attitude to the disease as well as the capacity to control his behaviour.
In addition to various mental conditions, neurotic people may have less protective immune systems; there is evidence that people who tend to be moody, nervous and easily stressed have a lower immune response to vaccination and may be more vulnerable to disease and other stressors.
The term was first used in 1776 by the physician W Cullen. In contemporary usage, neuroses include only disorders arising from psychic traumas and prolonged nervous tension. The predisposing factors are bodily constitution and trauma, intoxication, infection, and other debilitating diseases. Neurosis may be caused by an overpowering acute psychic trauma, such as the sudden loss of a loved one. Persistent psychic traumas, especially if they give rise to internal conflicts, may also result in neurosis. Overstrain of the nervous system is the basis for neuroses and this is more likely to occur in persons whose nervous systems are weak, imbalanced, or insufficiently responsive. Neurotic people are easily fatigued, easy excited, suffer rapid exhaustion, disturbed sleep habits, sweating, and unpleasant sensations in the chest near the heart.