Light Sensitivity

Apart from vision, human beings have many physiological and psychological responses to light. In rare individuals an atypical response may result in serious discomfort, disease, or injury. Some drugs have a photosensitizing effect. Properties of natural or artificial light that may abnormally affect people include:

Timing of light (upset of normal circadian rhythms, seasonal affective disorder, sleep disorders)
Intensity of light (photophobia, sunburn, skin cancer)
Wavelength of light ( in lupus, urticaria )
Rapid flickers in intensity of light may trigger or aggravate epilepsy or migraine headaches.
Other effects may include vertigo, or chronic fatigue syndrome.

Fibromyalgia Causes

The cause of fibromyalgia is currently unknown. However, several hypotheses have been developed.

Genetic predisposition

There is evidence that genetic factors may play a role in the development of fibromyalgia. For example, there is a high aggregation of fibromyalgia in families. The mode of inheritance is currently unknown, but it is most probably polygenic. Research has demonstrated that fibromyalgia is associated with polymorphisms of genes in the serotoninergic, dopaminergic and catecholaminergic systems. However, these polymorphisms are not specific for fibromyalgia and are associated with a variety of allied disorders (e.g. chronic fatigue syndrome, irritable bowel syndrome) and with depression.

Epstein Barr Virus

The Epstein-Barr virus (EBV), also called human herpesvirus 4 (HHV-4), is a cancer causing virus of the herpes family, which includes herpes simplex virus 1 and 2, and is one of the most common viruses in humans. Epstein-Barr virus occurs worldwide. It is known to cause infectious mononucleosis, is implicated in the causation of Burkitt’s lymphoma and Nasopharyngeal carcinoma, and is suspected to have a role in the pathogenesis of chronic fatigue syndrome.

Asthenia

Asthenia (Greek: ασθένεια, lit. lack of strength but also disease) is a medical term denoting symptoms of physical weakness and loss of strength.

A condition in which the body lacks or has lost strength either as a whole or in any of its parts. General asthenia occurs in many chronic wasting diseases, such as anemia and cancer, and is probably most marked in diseases of the adrenal gland. Asthenia may be limited to certain organs or systems of organs, as in asthenopia, characterized by ready fatiguability.

Asthenia is also a side effect of some medications and treatments, such as Ritonavir (a protease inhibitor used in HIV treatment), vaccines such as the HPV vaccine Gardasil and fentanyl patches (an opioid used to treat pain).

The condition is also commonly seen in patients suffering from chronic fatigue syndrome, sleep disorders or chronic disorders of the heart, lungs or kidneys.

Differentiating between psychogenic asthenia and true asthenia with muscular weakness is often difficult, and in time apparent psychogenic asthenia accompanying many chronic disorders is seen to progress into a primary weakness.