Association of sleep quality and mitochondrial DNA copy number in healthy middle-aged adults.

Objectives: Mitochondria contribute to various compromised health, yet the association between sleep and mitochondria remains unclear. This study investigated the association between sleep quality and mitochondrial function in healthy middle-aged adults in the Republic of Korea.

Method: This cross-sectional study recruited 238 middle-aged adults using convenience sampling. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). Mitochondrial function, represented by mitochondrial DNA copy number (mtDNAcn), was measured using real-time quantitative polymerase chain reaction on peripheral blood leukocytes. Multivariate linear regression analyses were performed to determine the association between sleep quality and mtDNAcn.

Results: Sleep quality was negatively associated with mtDNAcn (r = -.15, p = .025); the poor sleep quality group had a notably lower mtDNAcn compared to the good sleep quality group (t = 2.40, p = .017). Among the PSQI components, sleep latency was significantly associated with reduced mtDNAcn (r = -.18, p = .005). Univariate regression analysis revealed that mtDNAcn was significantly associated with education level (β = 0.15, p = .017), shift work (β = -0.17, p = .010), global PSQI score (β = -0.15, p = .025), and sleep latency (β = -0.18, p = .005). After adjusting for educational level and shift work in the final model, longer sleep latency was independently associated with reduced mtDNAcn (β = -.16, p = .011).

Conclusions: Poor sleep quality is associated with reduced mtDNAcn, suggesting a potential biological mechanism whereby poor sleep quality, specifically long sleep latency, accelerates cellular aging and impairs health through mitochondrial dysfunction. These findings enhance our understanding of the health effects of sleep quality and highlight the importance of screening and intervention strategies for mitochondrial dysfunction.