Effect of Sleep Quality on Mitochondrial DNA Copy Number in Eveningness Chronotypes.

ABSTRACT

OBJECTIVE: To determine the effect of sleep quality on mitochondrial DNA copy number in eveningness chronotype. STUDY DESIGN: Cross-sectional study. Place and Duration of the Study Department of Physiology, Islamic International Medical College, in collaboration with Genetic Resource Centre, from August 2022 to May 2023. METHODOLOGY: A total of 80 participants with eveningness chronotype based on the Morningness-Eveningness Questionnaire were recruited. The participants' sleep quality was assessed using Pittsburg Sleep Quality Index (PSQI). Accordingly, they were categorised into Group A (good sleep quality) and Group B (poor sleep quality) with 40 participants in each group. After extracting DNA using the Chelex method, mitochondrial DNA copy number of all participants was measured using the quantitative polymerase chain reaction. The mean values in both groups were analysed by Independent-samples t-test. RESULTS: Analysis of mitochondrial DNA copy number in both groups showed normal distribution after being transformed into logarithmic values. The mean value of Group A (2.65 ± 0.26) exhibited a significant increase in mitochondrial DNA copy number (95% CI 0.18, 0.44; p <0.001) as compared to that in Group B (2.34 ± 0.29). CONCLUSION: People with good sleep quality have a higher mtDNA-CN than those with poor sleep quality. Good sleep quality may counteract negative effects of increased oxidative stress brought on by eveningness behaviour, thus leading to better mitochondrial function and increased mitochondrial biogenesis that was indicated by higher mtDNA-CN in individuals who experience good sleep quality. KEY WORDS Mitochondria, Mitochondrial DNA copy number, Sleep quality, Chronotype.