Muscle Injury in Sleep Theory of Morning Muscular Pains in Fibromyalgia
This is the hypothesis to explain the common symptom of morning pains and morning stiffness in fibromyalgia. It postulates that is due to failed muscular repair or micro-injury in sleep. The theory is unproven, but there are several lines of evidence in favour of it:
- Sleep deprivation studies by Moldofsky were able to induce muscular pain in healthy subjects. Moldofsky writes: “In sleep studies of (a) patients with the "fibrositis syndrome" and (b) healthy subjects undergoing stage 4 sleep deprivation, we observed in both groups the anomalous presence of alpha-rhythms in the non-rapid-eye-movement (NREM) sleep EEG. This phenomenon has been termed alpha-delta sleep. In the healthy subjects, stage 4 deprivation was accompanied by the temporary appearance of musculoskeletal and mood symptoms comparable to the symptoms seen chronically in the patients. It is suggested that the external arousing stimulus, which induced alpha-delta sleep in the subjects, is paralleled in the patients by an internal arousing mechanism. Such a mechanism, acting in competition with the NREM sleep system, would impair the presumed restorative function of NREM sleep and lead to the development of symptoms.” (Musculo-skeletal symptoms and non-REM sleep disturbance in patients with "fibrositis syndrome" and healthy subjects. Moldofsky H, Scarisbrick P, England R, Smythe H. Psychosom Med. 1975 Jul-Aug;37(4):341-51.)
As Dattilo et al. point out: “Sleep is essential for the cellular, organic and systemic functions of an organism, with its absence being potentially harmful to health and changing feeding behavior, glucose regulation, blood pressure, cognitive processes and some hormonal axes. Among the hormonal changes, there is an increase in cortisol (humans) and corticosterone (rats) secretion, and a reduction in testosterone and Insulin-like Growth Factor 1, favoring the establishment of a highly proteolytic environment.” (Sleep and muscle recovery: endocrinological and molecular basis for a new and promising hypothesis. Dattilo M, Antunes HK, Medeiros A, Mônico Neto M, Souza HS, Tufik S, de Mello MT. Med Hypotheses. 2011 Aug;77(2):220-2.) (For additional information on the impact of sleep on pain see: Moldofsky H. Rheumatic manifestations of sleep disorders. Curr Opin Rheumatol. 2010 Jan;22(1):59-63.