Fatigue and sarcoidosis.

In the morning a man walks with his whole body in the evening only with his legs (Emerson). Fatigue is a common symptom. It is responsible for an estimated 10±15 million clinic or office visits annually in the USA. As an isolated symptom, fatigue is seldom a cause for concern. However, fatigue in association with a systemic illness can be ominous. Although interest in understanding the pathogenesis of fatigue is of relatively recent onset, the symptom has been with us forever. As Samuel Butler so elegantly stated "Life is one long process of getting tired" [1]. Fatigue may be transient or self-limiting and chronic or persistent. Transient fatigue is often associated with viral illness, overwork, stress, sleep deprivation, jet-leg and other temporary infirmities. Persistent or chronic fatigue may signify an associated serious, systemic illness including tuberculosis, cancer, diabetes mellitus, hypothyr-oidism, adrenal deficiency, anaemia or an autoimmune disorder. Sleep disorders constitute an important cause of fatigue. The occurrence of fatigue in sarcoidosis is well known, but the exact incidence has not been established and varies from 30±70% depending on age, sex, race and organ involvement by the granulomatous process [2, 3]. Four types of fatigue can be recognized in sarcoidosis. 1) Early-morning fatigue, where the patient either is not able to arise or arises with feelings of inadequate sleep. This type of fatigue is also seen in patients with autoimmune diseases and may reflect troublesome muscle or joint pains or sleep disorders including sleep apnoea syndrome [4]. 2) Intermittent fatigue, where the patient wakes up normally but after a few hours of activity, feels tired and exhausted. After a short rest of an hour or so, the patient is able to resume activity, only to be succumbed soon after by another episode of fatigue. The patient learns to pace his or her activities throughout the day with periods of rest alternating with periods of activity. Intermittent fatigue may last for days, weeks or months. 3) Afternoon fatigue, where the patient arises in the morning with adequate energy but "runs out of gas" or "feels washed up" in the early afternoon. These patients compare their fatigue to "having a flu-like syndrome". The feeling of exhaustion and sleepiness when not in bed and cannot get to bed is described by many of these patients as the "meanest feel-ing". Finally, the patient goes to bed early and stays there until the next morning. 4) …