Understanding the different relationships between mood and sleep disorders in several groups of non-oncological patients with chronic pain.

Objective: To compare sleep dimensions in patients suffering from chronic pain of different origins, and with a group of pain-free subjects. To analyze the relationship between depression and/or anxiety and sleep disorders in musculoskeletal, neuropathic, and fibromyalgia patients.

Methods: This cross-sectional study included patients diagnosed with neuropathic pain (NP) (n = 104), musculoskeletal pain (MSK) (n = 99), or fibromyalgia (FM) (n = 51), and pain free subjects (n = 72). Information about sleep dimensions (MOS-sleep), duration and intensity of pain (Visual Analog Scale), and anxiety and depression (Hospital Anxiety and Depression scale) was collected.

Results: Of the 254 patients with chronic pain (PCP) studied, the mean pain intensity was 6.6 (SD = 1.9), with an average duration of 9 years. The scores in all sleep dimensions of the MOS-sleep were higher in CPP (more disturbances) compared to pain free patients, and differences were observed among the three groups of PCP, with FM most severely affected. Anxiety (β = 1.3), depression (β = 1.1), intensity (β = 1.7), and duration of pain (β = 0.04) were associated with more sleep problems in MSK patients. In contrast, anxiety (β = 2.5) and duration of pain (β = 0.05) were negatively related to sleep in the NP patients, and only depression (β = 1.3) affected FM patients.

Conclusions: The sleep pattern differs among groups of PCP in the presence or absence of mood disorders. Understanding these disorders in each specific group of PCP is fundamental, and it can contribute to improve the clinical situation of the patients and better orientating therapeutic strategies.