Not everyone has a work schedule that resembles the traditional 9-to-5 day.
Almost 15 million Americans work full time on an evening shift, night shift, rotating shifts or other employer-arranged irregular schedules, according to 2004 data from the U.S. Bureau of Labor Statistics and reported by the Centers for Disease Control and Prevention (1). Also, many adults in the U.S. work 50 or more hours per week.
This is not only the trend in the U.S. People all over the world are involved in shift work or long work hours. It can be due to a desire to earn extra money, loyalty to the profession, a need for a job, work pressure or not completing work by the given deadline.
Shift workers commonly include doctors and nurses, pilots, bridge and road construction workers, police officers and firefighters, customer service representatives, food service workers and commercial drivers (2).
Whatever the reason, if you are doing shift work or working long hours, it can be bad for your health. It would be easy to attribute these health impacts to reasons other than your work schedule. Being aware of the health risks, you can take steps to address any problems as soon as you notice them.
Here are some of the effects of shift work on your health.
1. Hampers Sleep
Working in shifts or for long hours can have deleterious effects on your sleep.
First of all, people who work the night or evening shift often get fewer than six hours of sleep a day. Shift workers are also more likely to experience lower levels of serotonin, the “feel-good hormone,” than non-shift workers, which in turn impacts sleep.
A study published in Sleep Medicine Clinics in 2009 reports that shift work that includes the night will have pronounced negative effects on sleep, sleepiness, performance and accident risk.
Misalignment between internal circadian physiology and the required work schedule is thought to be a primary cause of sleepiness and sleep disruption due to shift work (3).
2. Raises Diabetes Risk
Working night shifts can put you at a higher risk of developing diabetes. This mainly happens due to shift work’s impact on insulin activity.
It also causes high blood pressure, obesity and unhealthy cholesterol levels, which are serious risk factors for diabetes as well as heart attacks and strokes.
A study published in PLOS Medicine in 2011 suggests that an extended period of rotating night shift work is associated with a modestly increased risk of Type 2 diabetes in women, which appears to be partly mediated through body weight. Proper screening and intervention strategies in rotating night shift workers are needed for prevention of diabetes (4).
A 2013 study published in the American Academy of Sleep Medicine suggests that night work may impair glucose tolerance, supporting a causal role of night work in the increased risk of Type 2 diabetes among shift workers (5).
A 2015 study published in Diabetology & Metabolic Syndrome also highlights the association between night and shift work and metabolic disorders, such as diabetes (6).
Additionally, shift work, particularly night shifts, can be challenging for people with diabetes, as it can cause potential difficulties related to mealtimes and medication schedules.
3. Leads to Obesity
Sleeping too little or sleeping “against” your body’s natural biological clock can lead to obesity.
A 2012 study published in Science Translational Medicine reports that too little sleep or sleep patterns that are inconsistent with our body’s “internal biological clock” may lead to increased risk of diabetes and obesity (7).
A 2015 study published in PLoS ONE found that cumulative night shift work showed significant associations with body mass index (BMI), waist circumference, hip circumference and waist-to-height ratio (8).
In a 2017 analysis of 28 published studies, night shift work was associated with a 29 percent increased risk of becoming obese or overweight.
4. Hampers Heart Health
Working the night shift is bad for your heart. Working late into the night also means your heart is working more and resting less.
Moreover, if you are under stress at work, your body releases the hormone cortisol, which is hard on your heart. This in turn can increase your risk for strokes, coronary artery disease and more.
Also, if you have sleep disturbance or are obese as a result of working the night shift, it raises your risk of heart-related problems.
A 2012 study published in the British Medical Journal analyzed several studies and showed that working the night shift could account for 7 percent of heart attacks that occurred in 2009 and 2010 in Canada, as well as 1.6 percent of ischemic strokes and 7.3 percent of coronary events during that time period (10).
Earlier, a 2008 study published in the Cardiovascular Journal of Africa found that shift work may be associated with an increased risk of cardiovascular disease for several reasons. Disturbed circadian rhythms, lifestyle changes and psychosocial stress are all factors that are frequently mentioned (11).
Later, a 2016 study published in JAMA found that among women who worked as registered nurses, a longer duration of rotating night shift work was associated with a statistically significant, but small absolute increase in coronary heart disease risk.
However, more research is needed to explore whether the association is related to specific work hours and individual characteristics (12).
5. Makes You Depressed
Shift work can have an impact on your mental health. The pressure, stress and sleep disturbance all play a major role in contributing to mood disorders like depression.
Sleep disturbance associated with shift work is a very important risk factor for depression, bipolar disorder and suicidality.
A 1997 study in the International Journal of Occupational and Environmental Health showed that depression occurs at a higher rate among shift workers than non-shift workers. Also, the rate was higher in women than men (13).
In a 2008 study in the International Journal on Disability and Human Development, researchers found that shift work can increase the risk of developing or aggravating mood disorders, at least in vulnerable individuals (14).
6. Causes Gastrointestinal Problems
Shift work is also not good for your gastrointestinal health. In fact, it can cause or worsen symptoms of nausea, diarrhea, constipation and some functional bowel diseases like irritable bowel syndrome (IBS).
All this happens because shift workers, although they do not significantly modify their total calorie intake, often change the timing and frequency of eating as well as the content of their meals. Moreover, the food is often cold and is usually eaten in a hurry.
In a study published in the American Journal of Gastroenterology in 2010, researchers found that participants doing shift work, especially rotating shift work, were at an increased risk of developing IBS and abdominal pain that is independent of sleep quality. Circadian rhythm disturbances may have a role in the pathogenesis of IBS and abdominal pain (15).
A literature review published in 2010 in the Scandinavian Journal of Work, Environment & Health found that shift workers appear to have an increased risk of gastrointestinal symptoms and peptic ulcer disease.
However, control for potential confounders (such as smoking, age, socioeconomic status and other risk factors) was often lacking or insufficient in many of the studies examined (16).
In addition, a 2016 study published in the International Archives of Occupational and Environmental Health reports that night-shift work is a risk factor for erosive esophagitis. Avoidance of night-shift work and lifestyle modifications should be considered for prevention and management of gastroesophageal reflux disease (GERD) (17).
- The National Institute for Occupational Safety and Health (NIOSH). Centers for Disease Control and Prevention. https://www.cdc.gov/niosh/topics/workschedules/. Published April 02, 2018.
- Shift Work and Sleep. National Sleep Foundation. https://sleepfoundation.org/sleep-topics/shift-work-and-sleep.
- Sleep Loss and Fatigue in Shift Work and Shift Work Disorder. Sleep medicine clinics. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2904525/. Published June 01, 2009.
- Rotating Night Shift Work and Risk of Type 2 Diabetes: Two Prospective Cohort Studies in Women. PLoS Medicine. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3232220/. Published December 2011.
- Night work may impair glucose tolerance. ScienceDaily. https://www.sciencedaily.com/releases/2013/06/130603114146.htm. Published June 03, 2013.
- Shift work and its association with metabolic disorders. Diabetology & Metabolic Syndrome. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4436793/. Published 2015.
- Less sleep, disrupted internal 24-hour clock means higher risk of diabetes and obesity. EurekAlert! https://www.eurekalert.org/pub_releases/2012-04/bawh-lsd040612.php. Published April 11, 2012.
- Association of Rotating Night Shift Work with BMI and Abdominal Obesity among Nurses and Midwives. PLoS ONE. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4511417/. Published 2015.
- Night shift work linked to an increased risk of obesity. ScienceDaily. https://www.sciencedaily.com/releases/2017/10/171004084933.htm. Published October 04, 2017.
- Shift work linked to increased risk of heart attack and stroke. Shift work linked to increased risk of heart attack and stroke | The BMJ. http://www.bmj.com/press-releases/2012/07/26/shift-work-linked-increased-risk-heart-attack-and-stroke.
- Shift work and its effects on the cardiovascular system. Cardiovascular Journal of Africa. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3971766/. Published 2008.
- Association between rotating night shift work and risk of coronary heart disease among women. JAMA. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102147/. Published April 26, 2016.
- Shiftwork as a Risk Factor for Depression: A Pilot Study. International journal of occupational and environmental health. https://www.ncbi.nlm.nih.gov/pubmed/9891131. Published July 1997.
- The impact of work environment on mood disorders and suicide: Evidence and implications. International journal on disability and human development : IJDHD. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2559945/. Published 2008.
- The Impact of Rotating Shift Work on the Prevalence of Irritable Bowel Syndrome in Nurses. The American journal of gastroenterology. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2887235/. Published April 2010.
- Gastrointestinal disorders among shift workers. Scandinavian journal of work, environment & health. https://www.ncbi.nlm.nih.gov/pubmed/20101379/. Published March 2010.
- Impact of night-shift work on the prevalence of erosive esophagitis in shipyard male workers. International Archives of Occupational and Environmental Health. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4927591/. Published 2016.