Activity rhythms and clinical correlates in fibromyalgia.

Area of Science:

• Chronobiology
• Rheumatology
• Sleep Medicine

Background:

• Fibromyalgia syndrome (FMS) is a chronic condition characterized by widespread pain, fatigue, and cognitive difficulties.
• Disruptions in daily activity rhythms and sleep disturbances are commonly reported in FMS patients, but their specific associations with symptom severity require further investigation.

Purpose of the Study:

• To investigate the relationship between activity rhythm parameters and FMS-related symptoms.
• To determine if more robust and consistent activity rhythms are associated with reduced symptom burden in FMS.

Main Methods:

• A cohort of 292 FMS patients underwent 7-day actigraphy monitoring.
• Activity rhythm parameters, including Amplitude (activity range), Phi (timing of peak activity), and Mesor (mean activity), were extracted using a cosine model.
• Patients also completed validated questionnaires assessing pain, fatigue, mood, and physical impairment.

Main Results:

• A significant association was found between activity rhythm parameters and clinical FMS measures (R = 0.14, P < 0.001).
• Higher Amplitude, Mesor, and earlier Phi were independently linked to better outcomes in pain, fatigue, mood, and physical function.
• Low Amplitude and delayed Phi were associated with poorer sleep quality.

Conclusions:

• Activity rhythm regularity, mean activity levels, and timing of peak activity are significant correlates of symptom severity in fibromyalgia syndrome.
• These findings suggest that optimizing activity patterns may be a potential therapeutic target for improving FMS management and patient outcomes.