Date of Award
Spring 2021
Degree Name
Master of Medical Science (Physician Assistant)
Department
Physician Assistant; College of Health Sciences
First Advisor
Zachary Weik
Abstract
Introduction: Circadian Misalignment is a term used to describe a mismatch in one’s physiologically determined sleep patters and their actual sleep wake behaviors. Shift workers often end up in a vicious cycle of being in a state of chronic circadian misalignment, which then can lead to health problems, extreme fatigue, and insomnia, known as Shift Work Disorder (SWD).This has been studied in night shift workers who, when compared to daytime workers, have an increased risk of developing metabolic syndrome, type 2 diabetes, and coronary heart disease.These results are not dependent on any behavioral risk factors, such as smoking and poor diet, that typically complement shift work lifestyles, and increase as a function of time as a shift worker. There have been several studied interventions to help mitigate circadian misalignment in shift workers, though two of the least expensive, most popular, and easily accessible methodologies are exogenous melatonin use and timed exposure to bright artificial light. This paper will examine if melatonin or bright light therapy may be able to mitigate the poor cardiovascular effects seen as a result of shift work disorder.
Methods: A literature search was completed through PubMed, Academic Search Ultimate, and Google Scholar. Seven articles were selected based on their relevance to shift work and cardiovascular outcomes, study design, measurements, and results.
Results: Based on the literature review, melatonin and bright light were both effective in their phase shifting properties and had various notable effects such as lowering blood pressure, decreasing inflammatory markers and reducing carotid intima media thickness. Due to the major limitations and inconsistencies between studies, the conclusion that melatonin and/or bright light therapy can mitigate poor cardiovascular outcomes due to shift work disorder cannot be definitively supported through the data that was examined. However, the data does present a robust foundation and direction for future long-term studies that can determine the role of melatonin and bright light therapy in cardiovascular diseases due to SWD.
Discussion: All of the studies established that melatonin and bright light can each play a sizeable role in decreasing symptoms of shift work disorder, however the effectiveness of reducing poor cardiovascular outcomes is still being studied. Most of the studies did not use comparable populations, dosing, and timing criteria, making comparisons challenging. Additionally, many studies simulated shift work and in those who did use shift workers, the length of time working was not controlled for. Lastly, no studies examined the effects of the interventions chronically.
Conclusion: The differences in delivery, timing, and strength of these interventions, while difficult for comparison purposes, ensures that there is a wide variety of options for shift workers to individualize their treatments. There were no negative side effects determined with the use of either intervention in any of the studies. The potential benefits for an individual will likely outweigh the costs, though future research should consider studying long-term guidelines and more robust cardiovascular outcomes to determine a full picture of the effects these interventions may have on a shift-working patient.
Recommended Citation
Hirt, Alexandra, "Comparing Melatonin Use to Bright Light Therapy in Mitigating Cardiovascular Effects due to Shift Work Disorder in Shift Working Adults" (2021). Capstone Showcase. 79.
https://scholarworks.arcadia.edu/showcase/2021/pa/79
Comparing Melatonin Use to Bright Light Therapy in Mitigating Cardiovascular Effects due to Shift Work Disorder in Shift Working Adults
Introduction: Circadian Misalignment is a term used to describe a mismatch in one’s physiologically determined sleep patters and their actual sleep wake behaviors. Shift workers often end up in a vicious cycle of being in a state of chronic circadian misalignment, which then can lead to health problems, extreme fatigue, and insomnia, known as Shift Work Disorder (SWD).This has been studied in night shift workers who, when compared to daytime workers, have an increased risk of developing metabolic syndrome, type 2 diabetes, and coronary heart disease.These results are not dependent on any behavioral risk factors, such as smoking and poor diet, that typically complement shift work lifestyles, and increase as a function of time as a shift worker. There have been several studied interventions to help mitigate circadian misalignment in shift workers, though two of the least expensive, most popular, and easily accessible methodologies are exogenous melatonin use and timed exposure to bright artificial light. This paper will examine if melatonin or bright light therapy may be able to mitigate the poor cardiovascular effects seen as a result of shift work disorder.
Methods: A literature search was completed through PubMed, Academic Search Ultimate, and Google Scholar. Seven articles were selected based on their relevance to shift work and cardiovascular outcomes, study design, measurements, and results.
Results: Based on the literature review, melatonin and bright light were both effective in their phase shifting properties and had various notable effects such as lowering blood pressure, decreasing inflammatory markers and reducing carotid intima media thickness. Due to the major limitations and inconsistencies between studies, the conclusion that melatonin and/or bright light therapy can mitigate poor cardiovascular outcomes due to shift work disorder cannot be definitively supported through the data that was examined. However, the data does present a robust foundation and direction for future long-term studies that can determine the role of melatonin and bright light therapy in cardiovascular diseases due to SWD.
Discussion: All of the studies established that melatonin and bright light can each play a sizeable role in decreasing symptoms of shift work disorder, however the effectiveness of reducing poor cardiovascular outcomes is still being studied. Most of the studies did not use comparable populations, dosing, and timing criteria, making comparisons challenging. Additionally, many studies simulated shift work and in those who did use shift workers, the length of time working was not controlled for. Lastly, no studies examined the effects of the interventions chronically.
Conclusion: The differences in delivery, timing, and strength of these interventions, while difficult for comparison purposes, ensures that there is a wide variety of options for shift workers to individualize their treatments. There were no negative side effects determined with the use of either intervention in any of the studies. The potential benefits for an individual will likely outweigh the costs, though future research should consider studying long-term guidelines and more robust cardiovascular outcomes to determine a full picture of the effects these interventions may have on a shift-working patient.