A study conducted by researchers from the Department of Anaesthesiology of LKS Faculty of Medicine, The University of Hong Kong (HKUMed), has provided an insight into the effect of acute sleep deprivation at the molecular level.
Sleep enables our minds and bodies to rest after a long day’s work. More than just passive rest, however, sleep is an active process that is vital to mental and cognitive health, immune response and physical health. We have known for a long time that sleep loss is associated with various health problems, with many studies focussing on the adverse effect of short and long term sleep deprivation. Prolonged sleep loss and insufficient sleep recovery is an important risk factor for developing metabolic, cardiovascular and neurodegenerative diseases, as well as cancer. Previous research has revealed that sleep loss induces a disruption in the integrity of the neuro-immuno-endocrine system, thereby impairing immune responses. This disruption is often related to the release of proinflammatory mediators, although more research is needed to further define how sleep loss can trigger the proinflammatory response.
Research Methodology and Findings
In the current study, the team was able to quantify DNA damage directly in young adults who had acute sleep deprivation due to overnight shift work. The study involved 49 healthy full-time doctors who had their blood analysed at different time points. There were two groups of participants, one group required to perform regular night shift and the other who were working normal day time office hours. Baseline blood samples were taken from both groups of participants on a morning after three consecutive days of self-reported adequate, undisturbed sleep. Additional blood was sampled on the morning after night shift from the group with sleep deprivation, defined as sleeping less than two sleep cycles (3 hours). The blood was analysed for DNA damage and DNA repair gene expression. The doctors who did night work had lower baseline DNA repair gene expression and more DNA damage than participants who did not work overnight. After one night of acute sleep loss, DNA repair gene expression was decreased and DNA damage was increased.
There are three main messages from this study. Firstly, quantification of DNA damage and DNA repair may serve as a useful method for studying the effects of sleep loss and sleep interventions in future research. This may be an important tool to help us to evaluate the efficacy of various strategies to alleviate sleep loss. Secondly, in order to understand sleep function and mechanisms, researchers need to master molecular and genetic approaches. Lastly, the study finds that even one night of sleep loss is associated with quantifiable changes at the molecular level. This includes a significant increase in DNA damage and a decrease in DNA repair in otherwise healthy, young doctors who do shift work. If sleep loss is unavoidable, investigation and implementation of measures to ameliorate the adverse effects are needed.
The subjects of the study were young doctors required to perform night shift and has highlighted the impact of disrupted sleep in health care professionals. However, sleep problems and sleep disorders are not limited to healthcare professionals or people who undertake shift work, it is a public health problem. In fact, the Center for Disease Control and Prevention (CDC) has declared sleep disorder a public epidemic and the World Health Organization has listed night-time shift work as a probable carcinogen. Much more work is needed to fight the adverse effects of sleep deprivation.
About the Research Team
The research team for this study were Dr Gordon Wong, Associate Professor; Dr Vivian Yuen Man-ying, Honorary Clinical Associate Professor; and Dr Choi Siu-wai, Research Associate, of the Department of Anaesthesiology, HKUMed; and Dr Vivian Cheung Yuen-ting, Resident Medical Officer of the Department of Anaesthesia, Pamela Youde Nethersole Eastern Hospital.
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