Evaluation of Chronotype and Central Sensitization in Patients With Fibromyalgia Syndrome, Cross-sectional Study

Fibromyalgia Syndrome (FMS); It is a syndrome characterized by chronic pain occurring in more than one part of the body and accompanied by fatigue, sleep disturbance, impairment in quality of life and daily functionality. Although FMS is seen in different age groups, it is most common in middle-aged women. FMS is classified as central sensitization syndrome, in which there is an abnormal response to painful stimuli and the processing of nociceptive stimuli in the central nervous system. In patients with FMS, pain may cause sleep disturbances such as non-restorative sleep or difficulty initiating or maintaining sleep. It is estimated that 65-99% of patients with FMS experience sleep disorders. Circadian rhythms reflect 24-hour physiological and behavioral cycles within each individual. Based on individual differences in the timing of these innate rhythms, individuals can be divided into 3 phenotypes (i.e., chronotypes): morning type (M-highest level of alertness in the morning), evening type (E most active in the evening), and intermediate type (I-neither M nor E). Chronotype is explained by both genetic and environmental factors and can be considered a fairly robust trait throughout adulthood. A study assessing 1548 people with FMS with an online survey including questions about sleep quality, well-being, pain, chronotype and FMS impact shows that late chronotypes are more affected by fibromyalgia. In another study conducted in 2019, patients with FMS were grouped according to chronotype preferences and showed that there was a strong relationship between FMS severity and poor quality of life in evening individuals.

The aim of study is to examine the chronotype preferences of patients with fibromyalgia syndrome and the relationship between central sensitization and chronotype, and to examine its relationship with pain intensity, disability and quality of life.