Long-term effects and vulnerable groups Gastrointestinal (GI) disorders are common in shift workers and may be due to changes in circadian rhythms of gastrointestinal function, sleep deprivation leading to stress response and changes in immune function, or to types of foods available during these shifts. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get Original Essay Schernhammer and colleagues (2006) reported an increased risk of colon cancer in nurses who work 3 or more nights per month for 15 or more years. Psychological disorders are frequently reported, including depression and other mood disorders, personality changes and relationship difficulties. A review of 17 studies suggests that shift work increases the risk of cardiovascular disease by 40% compared to day workers. Possible mechanisms include impaired glucose tolerance, insulin resistance, elevated cortisol levels, and increased sympathetic activity. Studies of reproductive outcomes concluded that shift work was associated with a modest increase in miscarriages, preterm births, and reduced fertility in women. The effect on reproduction in men has not been analyzed due to an inadequate number of studies. A meta-analysis of 13 studies examining night work and breast cancer reported that night work was associated with a moderately elevated risk among women. Exposure to light at night reduces melatonin levels, increasing the risk of cancer. Shift work can also exacerbate pre-existing chronic conditions, making it difficult to control symptoms and disease progression. Shift work interferes with treatment regimens that include regular sleep times, avoiding sleep deprivation, controlling amounts and times of meals and exercise, or careful timing of medications that have circadian variations in effectiveness. Sood suggests several conditions that can be exacerbated by shift work: unstable angina or history of myocardial infarction, hypertension, insulin-dependent diabetes, asthma, psychiatric illnesses, substance abuse, gastrointestinal diseases, sleep disorders, and epilepsy requiring medication. Please note: this is just an example. Get a custom paper from our expert writers now. Get a custom essay Costa adds chronic renal failure, thyroid and adrenal disorders, malignancies and pregnancy to this list. Aging is also associated with lower tolerance for shift work, which may be due to age-related changes in sleep that may make it more difficult for older people to initiate and maintain sleep at different times of the day. These sleep changes can begin as early as their 30s and 40s, so some workers who initially adapted well to shift work during their youth may show more symptoms as they age. Caruso and colleagues reported that in terms of working long hours, overtime was associated with worse perceived overall health, increased injury rates, more illnesses, or increased mortality in 16 of 22 recently published studies. Dembe and colleagues, examining data from the National Longitudinal Survey of Youth, discovered a dose-response relationship, such that as the number of hours worked increased, injury rates increased accordingly. Trinkoff and colleagues found that long working hours were related to the incidence of musculoskeletal injuries and needlestick injuries.