The Health Effects of Disordered Sleep Patterns

Impact on Pulmonary Fibrosis

Disordered sleep, whether excessively short or long, has been linked to an increased risk of pulmonary fibrosis due to disruptions in the circadian clock.

The Circadian Clock Explained

The circadian clock is an internal mechanism that regulates nearly all cellular activities in the human body. This internal clock governs physiological and behavioral changes on a 24-hour cycle, prominently influencing sleep and wakefulness. Additionally, various cellular and molecular processes, including hormone secretion and metabolism, adhere to this circadian rhythm.

Circadian Influence on Lung Function

The lungs are classified as circadian organs, responding to the body’s internal clock. Research indicates that bronchial epithelial cells lining the airways exhibit a distinct circadian rhythm, while the alveolar cells, which make up the tiny air sacs in the lungs, show weaker circadian properties. Recent findings published in the Proceedings of the National Academy of Sciences suggest that individuals with pulmonary fibrosis may experience heightened clock oscillations in alveolar cells, potentially contributing to the disease’s development. This study involved collaboration among researchers from the Universities of Manchester, Oxford, Newcastle, University College London, and Toronto and was funded by the Manchester University NHS Foundation Trust.

Lung Fibrosis and Disordered Sleep Patterns

Understanding Pulmonary Fibrosis

Pulmonary fibrosis is a chronic respiratory condition characterized by lung tissue scarring and impaired lung function. Various cell types are involved in the disease’s progression, prominently featuring fibroblasts that excessively secrete collagen, leading to the thickening and stiffening of lung tissue.

Research Insights from Animal Studies

Experiments conducted on mice revealed that altering core circadian signals can influence the fibrotic process in the lungs, increasing susceptibility to pulmonary fibrosis. Researchers specifically manipulated the core circadian clock protein REVERBα. Mice genetically engineered to lack this protein exhibited greater lung fibrosis, indicating that REVERBα plays a critical role in fibroblast activation. Conversely, treating human lung fibroblasts with a common REVERBα ligand resulted in decreased collagen secretion, highlighting potential therapeutic pathways.

Human Data and Circadian Risk Factors

Utilizing data from the UK Biobank, researchers established a link between pulmonary fibrosis risk and several circadian-related factors. Individuals sleeping less than four hours or more than eleven hours per day were found to be two to three times more likely to develop the disease compared to those averaging seven hours nightly. Additional risk factors included chronotype, or the tendency to stay up late, and shift work.

Research Findings and Implications

Contributions from Researchers

Dr. John Blaikley and Dr. Peter Cunningham from the University of Manchester co-authored the study emphasizing the adverse health consequences of disrupted sleep patterns. Dr. Blaikley remarked, “The discovery that the body clock is potentially a key player in pulmonary fibrosis opens new avenues for treatment and prevention. Further research is essential to establish causation and reproducibility. If confirmed, optimizing sleep duration may mitigate the effects of this debilitating disease.”

Therapeutic Potential of Circadian Research

Dr. Cunningham elaborated on the therapeutic implications of their findings, stating, “It is intriguing to consider that clock activity is heightened in fibrotic disease. Previous research has highlighted the circadian clock’s role in various health issues, including infection, cancer, and diabetes. The involvement of circadian rhythms in fibrosis suggests that modifying these oscillations may provide a valuable therapeutic strategy.”

References

Cunningham PS, Meijer P, Nazgiewicz A, et al. The circadian clock protein REVERBα inhibits pulmonary fibrosis development. Proc Natl Acad Sci U S A. 2020;117(2):1139-1147. doi:10.1073/pnas.1912109117
Addelman, M. Short or long sleep associated with Pulmonary Fibrosis. EurekAlert! (2019). https://www.eurekalert.org/news-releases/841651