Shift work disorder (SWD)
Approximately 15-30% of the working population engage in night shift work, including healthcare workers, factory workers, and emergency services. According to a recent meta-analysis published in Frontiers in Psychology, at least a quarter of these shift workers suffer from a condition known as shift work disorder (SWD), which is characterized by difficulty initiating and maintaining sleep when needed due to conflicting work and sleep schedules. SWD is commonly associated with impaired daily functioning as well as increased mental health strain. One of the major driving forces behind SWD is the mismatch between one’s work/sleep schedules and the earth’s natural day/night cues (e.g., sunlight), as this causes major disruptions to the body’s circadian rhythm, or “internal clock”.
Links between shift work and negative health outcomes
A 2022 review published in the Journal of Clinical Sleep Medicine suggests that people who work night shifts (particularly those suffering from SWD) are at a higher risk of developing serious health problems, including but not limited to: diabetes, heart disease, mental health disorders, and certain types of cancer. Whilst the exact mechanisms behind these associations are still being investigated, some potential factors have been identified.
Circadian rhythms play a crucial role in regulating metabolic function by controlling hormone levels and patterns of energy expenditure across a 24-hour cycle. Therefore, disruptions to one’s circadian rhythm due to shift work can throw the body’s metabolism out of balance. These metabolic imbalances have been suggested to be a significant factor contributing to insulin resistance and impaired glucose regulation in diabetes, as well as increased blood pressure and altered cardiac output in heart disease. Furthermore, altered hormone levels from circadian disruption have also been linked to the development and progression of colorectal and prostate cancers.
Unsurprisingly, shift workers are more likely to experience chronic sleep deprivation or other sleep-related disorders, which can have negative consequences for both mental health and neurological function. Additionally, working the night shift also means that you need to sleep during the day when most of your friends and family would be awake. In many cases, this can lead to isolation and disturbed social patterns that further impact on mental health.
Abnormal eating habits may also be a significant factor contributing to the negative effects of shift work on health. Compared to those that work a regular daytime schedule, shift workers with rotating schedules tend to eat more erratically, snack more frequently during the night, and eat food that is less healthy and more calorie-dense. As a result, shift workers are at a higher risk of obesity, which itself is a major risk factor for health and ageing.
What can shift workers do to protect their health?
In a post from the Harvard Medical School, associate professor of sleep medicine Dr. Eric Zhou provides some guidance on how shift workers can help improve their sleep, and thus protect their health. For example, he advises that night shift workers should try to minimize their exposure to bright light between leaving work and going to sleep. One simple way to achieve this is to use blackout curtains in the bedroom that drastically reduce the amount of natural sunlight – essentially “fooling” the brain into thinking it is nighttime when you are trying to sleep. Another point he stresses is the importance of allocating dedicated time for catching up on sleep during days off from work. However, this is often easier said than done, since many shift workers find that those days off are one of the few times when they can catch up with friends and family. Despite this, it is important to ensure that social commitments do not come at the cost of sleep.
References
Pallesen S., et al. (2021). Prevalence of Shift Work Disorder: A Systematic Review and Meta-Analysis. Front. Psychol., 12, 638252. https://doi.org/10.3389/fpsyg.2021.638252
Wu Q.J., et al. (2022). Shift work and health outcomes: an umbrella review of systematic reviews and meta-analyses of epidemiological studies. J Clin Sleep Med, 18, 653–662. https://doi.org/10.5664/jcsm.9642
Shi H., et al. (2022). Rotating Night Shift Work and Healthy Aging After 24 Years of Follow-up in the Nurses’ Health Study. JAMA network open, 5(5), e2210450. https://doi.org/10.1001/jamanetworkopen.2022.10450
Kamyab P., et al. (2023). Sleep disturbance and gastrointestinal cancer risk: a literature review. Journal of Investigative Medicine, 71(3), 163-172. https://doi.org/10.1177/10815589221140595
Clark A.B., et al. (2023). Dietary Patterns under the Influence of Rotational Shift Work Schedules: A Systematic Review and Meta-Analysis. Advances in Nutrition, 14(2), 295-316. https://doi.org/10.1016/j.advnut.2023.01.006
Salamon S. (2023). Shift work can harm sleep and health: What helps? Harvard Health Publishing. https://www.health.harvard.edu/blog/shift-work-can-harm-sleep-and-health-what-helps-202302282896
