Misalignment between subjective and objective sleep in chronic pain: The role of depressive symptoms

Poor sleep is consistently reported by chronic pain patients, while physiological sleep findings remain inconclusive. Limited evidence suggests depression may account for this discrepancy. This study investigated subjective-objective discrepancies in sleep efficiency and sleep disturbance in pain patients, and the mediating role of depressive symptoms in the effect of pain on subjective sleep.

From 1709 consecutive diagnostic polysomnography (PSG) patients, 45 patients with chronic pain conditions (CPC) and 161 without CPC were selected after excluding other major medical and psychiatric conditions. PSG, Pittsburgh Sleep Quality Index (PSQI), Insomnia Severity Index (ISI), pain and depression scales were analyzed using MANCOVA, multiple regression, and mediation models controlling for age, sex, and BMI.

PSG measures did not differ between the groups (all p > 0.09); however, CPC patients reported significantly worse sleep (PSQI Global: p = 0.016; PSQI sleep disturbance (SDist): p = 0.002; ISI: p = 0.054). In all subjects, PSQI-derived sleep efficiency (SE) significantly related to PSG-SE (p = 0.042) and characteristic pain intensity (CPI, p = 0.039) but not CPC presence; depressive symptoms fully mediated both relationships (p = 0.022 and p = 0.004, respectively). PSQI SDist was associated with CPI (p < 0.001) and CPC (p < 0.001); depressive symptoms partially mediated the relationship with CPI (p < 0.001).

In chronic pain, subjective sleep diverges from PSG data. Experienced pain intensity, CPC diagnosis and depressive symptoms exert distinct effect on different aspect of sleep perception. Cognitive-emotional factors and physiological processes beyond standard PSG analysis may play roles in these effects. Our results suggest a cautious interpretation of self-reported sleep and support integrating multiple methods of sleep assessment.