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Is shift work harming your health? Here's how to find out

August 15, 2021 at 4:00 a.m.

Over the last couple of months, this column has discussed some of the known health risks of shift work and how to mitigate those risks. If you missed the last couple of issues of HER, go back and read them now for a better understanding of this article's topic.

Shift work is defined as having work hours during the time in which most people are asleep. This includes working hours that begin at night or in the early hours of the morning.

Because these work hours go against our natural circadian rhythms and can cause a decoupling of the body's built-in clocks (the suprachiasmatic nucleus, or SCN, located in the hypothalamus and the peripheral clocks located in various tissues throughout the body), shift workers have an increased risk of cancer, dementia, diabetes, non-alcoholic fatty liver, cardiovascular disease, and a weakened immune system.

However, the good news is that these risks can be greatly mitigated by keeping the body's central and peripheral clocks aligned (the "how to" is explained in last month's issue), and by proactively tracking health biomarkers in order to detect minor health issues before they become big ones.

So let's get right to it. These are the biomarkers to track and why.

Blood glucose

Shift workers are at an increased risk of developing diabetes, but early detection of abnormal glucose metabolism and prediabetes is difficult with random blood glucose testing with standard glucometers or serum blood tests.

Continuous glucose monitoring with a prescription device such as a Freestyle Libre, which monitors interstitial glucose continually and relays glucose readings every five minutes to a phone app, could help shift workers identify whether eating at night or in the very early morning hours elicits unhealthy blood glucose levels.

Being able to get immediate feedback on how particular meals affect blood glucose levels may also be able to help shift workers make better food choices. Likewise, seeing the immediate positive benefits of exercise, physical activity, and adequate sleep on blood glucose may help incentivize healthy lifestyle choices.

Good Glucose Inc. is developing a mobile app that combines continuous glucose monitoring with machine learning and gamification to provide personalized nutrition and lifestyle recommendations to its users in a way that makes healthy choices fun and approachable. Anyone can sign up to be an early beta tester of the app before it's released to the public at


Melatonin (a hormone produced in the epithalamus of the brain) rises at night in response to a lack of blue light from the sun, but in night shift workers, melatonin production is suppressed by the presence of blue light from fluorescent lighting and electronics. Then during the daytime when these workers are trying to sleep, melatonin production can be suppressed by sunlight shining through a bedroom window.

Often thought of as just a sleep hormone, melatonin has a wide range of physiological functions including modulating the immune system to protect against infections, cytokine storm, and cancer.

Having healthy levels of melatonin during sleep may prevent a wide range of health conditions.

Dried Urine Testing for Comprehensive Hormones, or DUTCH, is an accurate, non-invasive way to measure melatonin levels in shift workers to determine whether sustained-release, low-dose melatonin supplementation is needed.


In healthy individuals, cortisol (a steroid hormone produced by the adrenal cortex above the kidneys) rises rapidly upon waking in the mornings and gradually decreases as the day progresses. Because sleep suppresses cortisol production, night shift workers may experience a peak in cortisol levels at night and a nadir in cortisol levels during the daytime just before going to sleep.

Regardless of sleep schedule, a healthy cortisol awakening response is essential for promoting a sense of wakefulness, reducing errors and traffic accidents, preventing hypertension and gastrointestinal diseases, and modulating the immune system.

A blunted cortisol awakening response (having low levels of cortisol upon starting the workday) could be a sign of psychological and physical burnout that could lead to chronic illness if not addressed.

On the other hand, an elevated cortisol awakening response signals ongoing job-related stress, pain, and poor glucose metabolism (high blood sugar).

Salivary cortisol testing of cortisol immediately upon waking, 30 minutes later, and 60 minutes later is currently the most accurate, non-invasive way to measure the cortisol awakening response. Subsequent salivary cortisol testing in the afternoon and at night is useful for gauging whether cortisol decreases appropriately and reaches its lowest point during sleep.

Alanine Transaminase (ALT)

A number of studies have found that shift work may trigger liver dysfunction and non-alcoholic fatty liver disease (NAFLD).

Alanine transferase, or ALT, is an enzyme concentrated primarily in the liver that facilitates a number of important functions in the body. An elevated ALT level in the blood is a sign of liver damage.

A comprehensive metabolic panel (CMP) is a blood test that includes an ALT test and is usually ordered as part of a routine wellness exam. An ALT above 40 U/L is common in night shift workers and should warrant further testing to assess the amount of liver damage that has occurred.

When liver damage is detected during the early stages, strict avoidance of high fructose corn syrup, following an anti-inflammatory diet, addressing abdominal obesity, adequate sleep, avoiding nighttime meals, and returning to a daytime work schedule are all strategies that can improve liver function and reverse NAFLD.

HDL, LDL, and Triglycerides

A systematic review and meta-analysis of night shift workers found increased levels of triglycerides and LDL, and decreased levels of HDL, among rotating night shift workers and permanent night shift workers. This type of lipid profile is strongly associated with cardiovascular disease.

Eliminating fatty meats, refined flour, and added sweeteners can reduce triglycerides and LDL, while exercise and EPA/DHA supplementation can increase HDL. Keeping these 3 biomarkers in an optimal range without the use of medications may help to prevent the development of cardiovascular disease in shift workers.


This is by no means a comprehensive list of all biomarkers that shift workers should be tracking in order to prevent disease. This is simply a starting point that shift workers may want to discuss with their doctor. Every individual has unique needs and may require other types of screening tests not mentioned here.

Questions or comments? Interested in DUTCH testing? Email [email protected] Go to


Dr. Jamie Koonce, DACM, L.Ac., Dipl.OM offers a health optimization program that is tailored to your specific health needs and goals. This may include a combination of laboratory testing, nutrition and lifestyle recommendations, herbal medicinals, nootropics, and acupuncture. Dr. Jamie is also the Founder & CEO of Good Glucose, Inc., a tech startup that is combining AI and gamification with continuous glucose monitoring in order to help individuals avoid the top 10 causes of morbidity and mortality in the United States. Learn more at



Sharma, Anu et al. "Glucose metabolism during rotational shift-work in healthcare workers." Diabetologia vol. 60,8 (2017): 1483-1490. doi:10.1007/s00125-017-4317-0

Carrillo-Vico, Antonio et al. "Melatonin: buffering the immune system." International journal of molecular sciences vol. 14,4 8638-83. 22 Apr. 2013, doi:10.3390/ijms14048638

Resuehr, David et al. "Shift Work Disrupts Circadian Regulation of the Transcriptome in Hospital Nurses." Journal of biological rhythms vol. 34,2 (2019): 167-177. doi:10.1177/0748730419826694

Wang, Feng et al. "Night shift work and abnormal liver function: is non-alcoholic fatty liver a necessary mediator?." Occupational and environmental medicine vol. 76,2 (2019): 83-89. doi:10.1136/oemed-2018-105273

Softic, Samir et al. "Role of Dietary Fructose and Hepatic De Novo Lipogenesis in Fatty Liver Disease." Digestive diseases and sciences vol. 61,5 (2016): 1282-93. doi:10.1007/s10620-016-4054-0

Adamovich, Yaarit et al. "Circadian clocks and feeding time regulate the oscillations and levels of hepatic triglycerides." Cell metabolism vol. 19,2 (2014): 319-30. doi:10.1016/j.cmet.2013.12.016

Lin, Yu-Cheng et al. "Long-term day-and-night rotating shift work poses a barrier to the normalization of alanine transaminase." Chronobiology international vol. 31,4 (2014): 487-95. doi:10.3109/07420528.2013.872120

Dutheil, Frédéric et al. "Shift work, and particularly permanent night shifts, promote dyslipidaemia: A systematic review and meta-analysis." Atherosclerosis vol. 313 (2020): 156-169. doi:10.1016/j.atherosclerosis.2020.08.015

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