Heyo again,
Yesterday I read this study on the relationship between sleep and cellular aging, focusing on the effect of poor sleep quality on mitochondrial function:
Seolbin Han, Dae-Kwang Kim, Sang-Eun Jun, Nahyun Kim, Association of sleep quality and mitochondrial DNA copy number in healthy middle-aged adults, Sleep Medicine, Volume 113, 2024, Pages 19-24, ISSN 1389-9457, https://doi.org/10.1016/j.sleep.2023.11.011 (https://www.sciencedirect.com/science/article/pii/S138994572300429X)
MY NOTES:
Inadequate sleep can accelerate cellular aging via
inducing changes in telomere length,
reducing mitochondrial function.
Mitochondria are receiving increasing attention as cellular aging biomarkers. Studies have shown links between mitochondrial DNA (mtDNA) and numerous diseases, including sleep disorders.
Mitochondria and sleep/circadian rhythm have a bidirectional link:
sleep and circardian rhythms affect energy expenditure,
mitochondria influence circadian oscillations and sleep-wake cycles.
Evidence from animal studies suggests that sleep disturbances may lead to mitochondrial damage. Some studies on humans have reported that short sleep duration and obstructive sleep apnea are associated with reduced mtDNAcn (number of mitochondrial DNA copies - a marker of mitochondrial function).
Methods and study design:
Han et al., 2023 investigated the potential link between sleep quality (evaluated using the PSQI-K assessment, in which a higher score means poorer sleep quality) and mitochondrial function in 238 healthy middle-aged Korean adults, collecting blood samples, extracting mitochondrial mtDNA and measuring it using qPCR.
Results:
The study found that poor sleep, particularly longer sleep latency (the amount of time needed to fall asleep), was associated with significantly reduced mtDNAcn. This suggests a potential biological mechanism whereby poor sleep quality accelerates cellular aging and impairs health through mitochondrial dysfunction.
Explanation:
The mechanism is not clear but it could have something to do with this:
sleep disturbance --> activation of the autonomic nervous system and the hypothalamus-pituitary-adrenal axis --> chronic systemic inflammation --> excessive ROS (reactive oxygen species) production --> oxidative stress --> disruption of mitochondrial networks & mitochondrial dysfunction
Interesting findings:
Shift workers such as nurses or firefighters had higher global PSQI scores (as would be expected) and reduced mtDNAcn compared to non-shift workers.
Interestingly, an association was found between education level and mtDNAcn: college graduates had lower mtDNAcn than high school graduates. This could be due to the higher stress levels of college graduates due to greater job demands.