Almost 15 million American adults don't work the typical 9-to-5, according to the Centers for Disease Control and Prevention. These employees clocking in for evening, overnight or other irregular shifts -- what's known as shift work -- are at a higher risk for a host of health problems that daytime desk jockeys may not necessarily face to the same degree.
Here's a look at what we know about the potential health effects of shift work:
Shift work hurts sleep.
Alamy
A study of police officers found a strong link between working the night or evening shift, and getting fewer than six hours of sleep a day.
The research, published in the journal Workplace Health & Safety, also showed that police officers who got fewer than six hours of sleep a day had more than a doubled risk of bad quality sleep, compared with those who got six or more hours of sleep a day.
And in another study in the journal SLEEP, University of Buenos Aires researchers found that shift workers were more likely to experience lower serotonin levels than non shift workers, which could thereby impact sleep, CBC reported. Serotonin, the "feel-good hormone," is also known to impact sleep.
The research, published in the journal Workplace Health & Safety, also showed that police officers who got fewer than six hours of sleep a day had more than a doubled risk of bad quality sleep, compared with those who got six or more hours of sleep a day.
And in another study in the journal SLEEP, University of Buenos Aires researchers found that shift workers were more likely to experience lower serotonin levels than non shift workers, which could thereby impact sleep, CBC reported. Serotonin, the "feel-good hormone," is also known to impact sleep.
It ups diabetes risk
ballyscanlon via Getty Images
In a review of the existing research on shift work and diabetes risk, researchers concluded that men in particular were more likely to develop the disease if they had irregular working hours.
Among 226,652 participants included in the review, those working night shifts had a 1.09 times greater risk of developing diabetes, according to the study, which was published in the journal Occupational & Environmental Medicine.
An earlier study in the journal PLoS Medicine showed that rotating shift workers had a higher Type 2 diabetes risk, likely because of shift work's impact on insulin activity, Time reported.
Among 226,652 participants included in the review, those working night shifts had a 1.09 times greater risk of developing diabetes, according to the study, which was published in the journal Occupational & Environmental Medicine.
An earlier study in the journal PLoS Medicine showed that rotating shift workers had a higher Type 2 diabetes risk, likely because of shift work's impact on insulin activity, Time reported.
Shift work raises obesity risk
Shutterstock
Sleeping too little or sleeping "against" your body's natural biological clock could increase the likelihood of developing diabetes or becoming obese, according to a study from Brigham and Women's Hospital researchers in the journal Science Translational Medicine.
While the study was small -- it only included 21 people! -- the findings are valuable because it was a controlled study, meaning it placed people in an environment where scientists decided how much sleep they got each day, and what time they were able to go to sleep.
"Since night workers often have a hard time sleeping during the day, they can face both circadian disruption working at night and insufficient sleep during the day," study researcher Orfeo M. Buxton, Ph.D., a neuroscientist at Brigham and Women's Hospital, said in a statement. "The evidence is clear that getting enough sleep is important for health, and that sleep should be at night for best effect."
While the study was small -- it only included 21 people! -- the findings are valuable because it was a controlled study, meaning it placed people in an environment where scientists decided how much sleep they got each day, and what time they were able to go to sleep.
"Since night workers often have a hard time sleeping during the day, they can face both circadian disruption working at night and insufficient sleep during the day," study researcher Orfeo M. Buxton, Ph.D., a neuroscientist at Brigham and Women's Hospital, said in a statement. "The evidence is clear that getting enough sleep is important for health, and that sleep should be at night for best effect."
Advertisement
It raises breast cancer risk
Alamy
Working the night shift raises a woman's risk of breast cancer risk by 30 percent, according to a study in the International Journal of Cancer.
Specifically, French researchers found that the breast cancer risk of women who worked the night shift for four years was especially clear, as well as those who only worked the night shift for three or fewer nights a week (meaning their daily rhythms were disturbed more often).
Specifically, French researchers found that the breast cancer risk of women who worked the night shift for four years was especially clear, as well as those who only worked the night shift for three or fewer nights a week (meaning their daily rhythms were disturbed more often).
It provokes negative metabolic changes
Alamy
Night shift work could lead to lower levels of leptin, the hormone known to play a role in regulating weight, as well as affect blood sugar and insulin levels, Health.com. reported.
The findings, published in 2009 in the journal Proceedings of the National Academy of Sciences, suggest that these changes could lead to a higher risk of serious health conditions like diabetes and heart disease, according to Health.com.
The findings, published in 2009 in the journal Proceedings of the National Academy of Sciences, suggest that these changes could lead to a higher risk of serious health conditions like diabetes and heart disease, according to Health.com.
It increases heart attack risk
crazydiva via Getty Images
Working the night shift could make you more likely to have a heart attack, according to a review of research published in the British Medical Journal.
The review included 34 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, CBC reported.
The review included 34 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, CBC reported.
Advertisement
Shift work increases risk of workplace injury
Alamy
Working the night shift could nearly double your risk of suffering a workplace injury, according to University of British Columbia researchers.
Their findings, published in the Scandinavian Journal of Work, Environment and Health, reveal that work injuries on a whole in Canada have gone down between 1996 and 2007, but they didn't go down at all among people who work at night.
"The disruption of normal sleep patterns due to shift work can cause drowsiness or fatigue, which can lead to workplace injuries," study research Imelda Wong, a Ph.D. candidate at the University of British Columbia's School of Environmental Health, said in a statement. "Our research shows that people working rotating and night shifts are more likely to experience an injury than those who work regular day hours."
Their findings, published in the Scandinavian Journal of Work, Environment and Health, reveal that work injuries on a whole in Canada have gone down between 1996 and 2007, but they didn't go down at all among people who work at night.
"The disruption of normal sleep patterns due to shift work can cause drowsiness or fatigue, which can lead to workplace injuries," study research Imelda Wong, a Ph.D. candidate at the University of British Columbia's School of Environmental Health, said in a statement. "Our research shows that people working rotating and night shifts are more likely to experience an injury than those who work regular day hours."
It ups depression risk
Mads Perch via Getty Images
Numerous studies have suggested that shift work could have an impact on mental health. For example, a 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.
And in a 2008 study in the International Journal on Disability and Human Development, researchers found that "shift work is suggested to increase the risk of developing or aggravating mood disorders at least in vulnerable individuals," though they also acknowledged that some experts say depression risk may have more to do with the actual job than working the night shift.
And in a 2008 study in the International Journal on Disability and Human Development, researchers found that "shift work is suggested to increase the risk of developing or aggravating mood disorders at least in vulnerable individuals," though they also acknowledged that some experts say depression risk may have more to do with the actual job than working the night shift.