Sleep and Fibromyalgia

Abstract

Fibromyalgia (FM) is a medically unexplained illness characterized by four quadrant pain lasting at least 3 months and accompanied by multiple areas of tenderness on palpation of the body using 4 kg force. FM occurs more often in women than men but is quite common in both sexes, occurring in approximately 3% of the population. Although sleep difficulties are not part of standard diagnostic criteria, insomnia complaints of poor and nonrestorative sleep are common and have been associated with intense of pain, fatigue, sleepiness, and cognitive difficulties in FM. FM frequently occurs in conjunction with chronic fatigue syndrome (CFS). CFS is a medically unexplained condition characterized by persistent or relapsing fatigue lasting at least 6 months, which substantially reduces normal activity. In addition to severe fatigue, one of the eight symptoms used for diagnosing CFS is “unrefreshing sleep”, and this sleeprelated problem is the most common complaint among CFS patients. Although, FM and CFS often have similar symptoms, including sleep-related complaints, differences between FM and CFS exist. In this chapter, we will review studies on sleep in FM and CFS patients in order to better understand differences between them. Polysomnographic studies have shown sleep problems in FM by using simple descriptive statistics, for instance, increased non-rapid eye movement (non-REM) Stage 1 sleep, reduced slow-wave (Stages 3 and 4) sleep, more arousals, prolonged sleep onset, reduced sleep efficiency, etc. Sleep problems in CFS shown by polysomnographic studies are quite similar to those in FM. However, we have shown that dynamic aspects of sleep, a new way of assessing sleep, are different between patients with CFS alone compared to those with CFS+FM. The probability of transition from rapid eye movement (REM) sleep to waking in CFS is greater than in healthy controls. Probabilities of transitions from waking, Stage 1 sleep, and REM sleep to Stage 2 and those from slow-wave sleep to waking and Stage 1 sleep are greater in FM+CFS than in healthy controls. Over the course of the many decades, sleep researchers have used simple descriptive statistics to characterize and summarize sleep architecture. While this methodology has