Association of cerebrospinal fluid FGF21 with sleep quality in Chinese adults.

Objective: This study aimed to examine whether FGF21 levels in cerebrospinal fluid (CSF) and plasma are associated with sleep quality, as measured by the Pittsburgh Sleep Quality Index (PSQI) scores, and to assess the correlation between FGF21 levels and sleep disorder severity.

Methods: We recruited 90 Chinese adult males undergoing anterior cruciate ligament reconstruction surgery, gathering sociodemographic and clinical characteristics. Sleep quality was assessed using the PSQI, and CSF samples were obtained for FGF21 analysis.

Results: Spearman's correlation analysis showed that CSF FGF21 levels were positively correlated with PSQI global scores (r = 0.51, p < 0.001), as well as with specific components, including sleep quality (r = 0.32, p < 0.01), sleep latency (r = 0.46, p < 0.001), sleep disturbances (r = 0.53, p < 0.001), and daytime dysfunction (r = 0.55, p < 0.001). CSF FGF21 levels also positively correlated with APOA1 levels. However, plasma FGF21 levels showed no correlation with these sleep parameters. Elevated CSF FGF21 levels were associated with higher PSQI scores and increased prevalence of prolonged sleep latency, sleep disturbances, and daytime dysfunction. The association between CSF FGF21 levels and sleep disorders remained significant after adjusting for age, BMI, education, living situation, marital status, and biochemical markers.

Conclusions: This study identifies a novel positive association between CSF FGF21 levels, rather than plasma FGF21, and sleep quality, as assessed by PSQI scores, particularly in subcategories including low sleep quality, prolonged sleep latency, severe sleep disturbances, and marked daytime dysfunction in healthy adults.