Role of Sleep Disturbance

Nighttime sleep disturbance is being examined in persons with FMS. First, scientists examining electrical activity of the brain in persons with fibromyalgia found that the deepest stages of sleep activity, involving the tall, broad wave forms (delta waves), were often disrupted by low amplitude, high frequency waves (alpha waves) characteristic of an aroused individual. Consequently, it is believed that people with the disorder tend to be roused repeatedly throughout the night since alpha waves tend to interrupt a person's delta sleep. This disturbance may result in the lack of the stage 4 sleep, the deepest and most restorative phase of sleep, considered to be important to the healing and regeneration of muscles and other body tissues. Therefore, sleep disturbance is considered to play a role in the muscle pain found in FMS, since muscles are nightly deprived of their time for renewal, rest, and repair.

Scientists have also found abnormally low levels of somatomedin C in persons with FMS. Somatomedin C is a growth hormone secreted by the kidney and is known to be important to maintaining good muscle and other soft tissue health. Its release stimulates the liver to release insulin-like growth factor (IGF1) and in combination these neurochemicals allow the body to repair the muscles during the night while resting. Furthermore, scientists have produced fibromyalgia-like symptoms and tender points in normal volunteers by depriving them of deep sleep for a few days, implying that these same changes can be produced by experimental deep sleep deprivation and therefore may result from secondary causes rather than primary causes.

Experimental disturbance of deep sleep in normal volunteers causes similar immune system changes, suggesting that the immune system changes may also be secondary to the sleep disorder. Levels of certain cytokines, a class of immune system hormones, are elevated in FMS. When these same cytokines are given to people to treat other disorders, fibromyalgia-like side effects are common. These findings suggests that FMS symptoms may be caused by elevated levels of certain cytokines produced by an immune system which is not functioning normally because of a chronic sleep disorder.

These explanations for sleep difficulties in FMS are by no means understood completely; they continue to be examined, as well as other plausible theories.