Fibromyalgia (FM) patients report early morning awakenings, awakening feeling tired or unrefreshed, insomnia, as well as mood and cognitive disturbances; they may also experience primary sleep disorders including sleep apnea. Longitudinal studies have demonstrated the chronic nature of these disturbances in patients with FM. A distinct relationship exists between poor sleep quality and pain intensity. Polysomnographic findings during sleep in these patients include an alpha frequency rhythm, termed alpha-delta sleep anomaly, which is also seen in normal controls during stage 4 sleep deprivation; deep pain induced during sleep in normal controls also causes this anomaly. Sleep architecture is altered in FM patients showing an increase in stage 1, a reduction in delta sleep, and an increased number of arousals. Before prescribing pharmacologic compounds aimed at modifying sleep, adequate pain control and sleep habits should be achieved; tricyclic antidepressants, trazadone, zopiclone, and selective serotonin reuptake inhibitors, however, may be required. More research is needed to elucidate the cellular and molecular mechanisms involved in the sleep disturbances occurring in patients with FM.