Working the night shift might raise a man's risk of prostate cancer by nearly three times, according to a new study in the American Journal of Epidemiology.

Researchers at the University of Quebec and the Centre INRS-Institut Armand-Frappier looked at whether working the night shift raised the risk of different cancers in men. Their analysis was based on 3,137 men who had had cancer at one of 11 different sites on their bodies, as well as 512 controls who didn't have cancer.

Researchers found specifically that working the night shift is linked with a 2.77 times higher risk of prostate cancer, as well as a 1.76 times higher risk of lung cancer, a 2.03 times higher risk of colon cancer, a 1.74 times higher risk of bladder cancer, a 1.31 times higher risk for non-Hodgkin's lymphoma, a 20.9 times higher risk for rectal cancer and a 2.27 times higher risk for pancreatic cancer.

While it's not exactly clear how night shift might affect cancer risk, "exposure to light at night can lead to a reduced production of the sleep hormone melatonin, inducing physiological changes that may provoke the development of tumors," study researcher Marie-Élise Parent, of the Centre INRS-Institut Armand-Frappier, said in a statement. "This hormone, habitually released in the middle of the night in response to absence of light, plays a pivotal role in hormonal functions and in the immune system."

Working the night shift has been linked with a myriad of other health conditions; click through the slideshow for more.

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  • Hurts Your Sleep

    A study of police officers found a strong link between working the night or evening shift, and <a href="http://www.huffingtonpost.com/2012/07/21/police-sleep-shift-work-_n_1686727.html">getting fewer than six hours of sleep</a> a day. The research, published in the journal <em>Workplace Health & Safety</em>, also showed that police officers who got fewer than six hours of sleep a day had more than a <a href="http://www.huffingtonpost.com/2012/07/21/police-sleep-shift-work-_n_1686727.html">doubled risk of bad quality sleep</a>, compared with those who got six or more hours of sleep a day. And in another study in the journal <em>SLEEP</em>, University of Buenos Aires researchers found that shift workers were more likely to experience <a href="http://www.cbc.ca/news/health/story/2007/08/02/serotonin-shift.html">lower serotonin levels</a> than non shift workers, which could thereby impact sleep, CBC reported. Serotonin, the "feel-good hormone," is also known to impact sleep.

  • Raises Breast Cancer Risk

    Working the night shift raises <a href="http://www.huffingtonpost.com/2012/07/01/shift-work-breast-cancer-night-sleep_n_1612486.html">a woman's risk of breast cancer</a> risk by 30 percent, according to a study in the <em>International Journal of Cancer</em>. Specifically, French researchers found that the breast cancer risk of women who <a href="http://www.huffingtonpost.com/2012/07/01/shift-work-breast-cancer-night-sleep_n_1612486.html">worked the night shift</a> for four years was <em>especially</em> 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).

  • Raises Obesity And Diabetes Risks

    Sleeping too little or sleeping "against" your body's natural biological clock could increase the likelihood of <a href="http://www.huffingtonpost.com/2012/04/11/shift-work-sleep-type-2-diabetes-obesity_n_1418394.html">developing diabetes or becoming obese</a>, according to a study from Brigham and Women's Hospital researchers in the journal <em>Science Translational Medicine</em>. 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 <a href="http://www.eurekalert.org/pub_releases/2012-04/bawh-lsd040612.php">circadian disruption</a> 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." Plus, another study in the journal <em>PLoS Medicine</em> showed that rotating shift workers had a <a href="http://healthland.time.com/2011/12/07/why-working-the-night-shift-may-boost-your-risk-of-diabetes/">higher Type 2 diabetes risk</a>, likely because of shift work's impact on insulin activity, <em>TIME</em> reported.

  • Increases Heart Attack Risk

    Working the night shift could make you more likely to <a href="http://www.huffingtonpost.ca/2012/07/26/shift-work-heart-health_n_1708093.html?utm_hp_ref=health-news&ir=Health%20News&ncid=edlinkusaolp00000008">have a heart attack</a>, according to a review of research published in the <em>British Medical Journal</em>. The review included 34 studies, and showed that working the night shift could account for <a href="http://www.huffingtonpost.ca/2012/07/26/shift-work-heart-health_n_1708093.html?utm_hp_ref=health-news&ir=Health%20News&ncid=edlinkusaolp00000008">7 percent of heart attacks</a> 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.

  • Provokes Negative Metabolic Changes

    Night shift work could lead to <a href="http://news.health.com/2009/03/03/night-shift-work-hard-on-heart/">lower levels of leptin</a>, 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 <em>Proceedings of the National Academy of Sciences</em>, suggest that these changes could lead to a higher risk of <a href="http://news.health.com/2009/03/03/night-shift-work-hard-on-heart/">serious health conditions</a> like diabetes and heart disease, according to Health.com.

  • Makes You More Likely To Be Injured At Work

    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 <a href="http://www.sjweh.fi/show_abstract.php?abstract_id=3124">the <em>Scandinavian Journal of Work, Environment and Health</em></a>, 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 <a href="http://www.publicaffairs.ubc.ca/2010/11/02/mr-10-163/">cause drowsiness or fatigue</a>, 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."

  • Ups Depression Risk

    Numerous studies have suggested that shift work could have an impact on mental health. For example, a study in <a href="http://www.ncbi.nlm.nih.gov/pubmed/9891131">the <em>International Journal of Occupational and Environmental Health</em></a> showed that depression occurs at a higher rate among shift workers than non shift workers. And in a 2008 study in the <em>International Journal on Disability and Human Development</em>, researchers found that "shift work is suggested to increase the risk of <a href="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2559945/">developing or aggravating mood disorders</a> 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.

  • Sleep Help for the Graveyard Shift

    In this health video you will gain some help so you can sleep when you work odd hours through the night.