In nature, humans are diurnal, so sleeping at night is our natural biological rhythm. In our modern world of artificial light and 24/7 activity, though, night shifts are common. Unfortunately, working the night shift can interfere with our sleep-wake cycle, and that can lead to health problems ranging from obesity to cancer to injuries. Your mental health can suffer as well.
One of the most serious health effects of night shift work is an increased risk of cancer. The effect of night shift work is significant enough that, in 2007, the World Health Organization listed “shiftwork that causes circadian disruption” as a probable carcinogen. Women who work at night, mainly flight attendants and nurses, have an increased risk of breast cancer. This increase in risk is consistent with experimental animal research showing increased tumors in animals kept in constant light, dim light at night, or simulated chronic jet lag. A number of epidemiological studies have also associated circadian disruption with cancers in diverse human organ systems, including ovarian, lung, pancreatic, prostate, colorectal, and endometrial cancers, non-Hodgkin’s lymphoma, osteosarcoma, acute myeloid leukemia, head and neck squamous cell carcinoma, and hepatocellular carcinoma.
Other Chronic Health Problems
In addition to cancer, epidemiological studies have found an increase in cardiovascular disease in night shift workers. Shift work is also associated with an increased rate of gastrointestinal, metabolic, and reproductive problems. Moreover, night shift workers show greater rates of overweight and obesity. According to the Centers for Disease Control and Prevention, night work is also associated with an increased risk of diabetes, impaired immune function, and aging.
Mental health and well-being
Working the night shift can lead to impaired mental and physical functioning, including emotional fatigue and a weakened immune system. The sleep disorder known as shift work disorder leads to a number of psychological difficulties, including difficulty concentrating, insomnia, sleep that feels unrefreshing or insufficient, and excessive sleepiness when you need to be awake. Night shift work also tends to strain personal relationships, such as marriage and family. As a result, night shift workers suffer from a higher risk of depression.
When we don’t get enough quality sleep, we wake up less alert and able to concentrate, make decisions, and engage fully in activities. This can lead to injuries from accidents, from car crashes to needle sticks. Especially at risk are transportation workers, such as truck drivers who drive long distances at night, an especially high-risk profession. Nurses working at night, another occupation with substantial risk, are injured more often than those working during the day. According to a recent review by University of Basel researchers Uehli and colleagues, approximately 13% of work injuries could be attributed to sleep problems.
Solutions: sleep hygiene, light therapy, pharmacology, and daily exercise
As living beings, we have a hard-wired biological clock known as the circadian timing system. This circadian rhythm is based on two things: an endogenous timing system of approximately 24 hours, and a system that takes into account cues like daylight and activity. In order to minimize problems associated with night shift work, you can do two things. One is to try to make the night shift more regular, in line with our natural 24-hour biological clock. If you rotate, it is better if you work the night shift for a few weeks, then do the day shift for a few weeks, rather than doing a few night shifts and a few day shifts every week. In addition, try to shift in the positive direction—that is, change your shifts so that you are waking up later for the new shift rather than earlier.
The other thing you can do is adjust your environmental cues. Light is a big one. Make sure that your sleeping area is darkened when it’s time to sleep, and if you wake up in the dark, use a light therapy box. Light therapy boxes emit either bright white or blue light. Simply sit in front of the box, with the box shining on your face at about a 45 degree angle, for about 15 minutes when you first wake up. You will find that you are less sleepy throughout the day, and that you will adjust more quickly to the new routine; people often wake up just before their regular light box time, just as they would wake up with the sun on a natural schedule. Exercise is also key; regular exercise during your awake time can counteract many of the health effects associated with night shift work. Some individuals find the natural supplement melatonin, taken just before the time they want to go to sleep, to be helpful. Finally, while medications can help you get to sleep and stay awake, these are options of last resort, as they can be habit-forming and can be harmful to natural sleep architecture. Your doctor can help you decide whether it makes sense for you to take any medication, and if so, which type would be best for you.
References and further reading:
Journal of Advanced Nursing: Twenty-Four/Seven: A Mixed-Method Systematic Review of the Offshift Literature
International Agency for Research on Cancer, World Health Organization
Progress in Molecular Biology and Translational Science: The Circadian Clock in Cancer Development and Therapy
Progress in Brain Research: The Impact of the Circadian Timing System on Cardiovascular and Metabolic Function
Sleep Medicine Reviews: Sleep Problems and Work Injuries: a Systematic Review and Meta-Analysis
Journal of Nature and Science of Sleep: Shift Work: Health, Performance and Safety Problems, Traditional Countermeasures, and Innovative Management Strategies to Reduce Circadian Misalignment
National Sleep Foundation: Shift Work and Sleep
Centers for Disease Control and Prevention (CDC): Sleep and Work
National Sleep Foundation: Shift Work Disorder
Healthcare Journal of New Orleans: The Therapeutic Benefits and Risks of Light
Centers for Disease Control and Prevention (CDC): Truck Driver Safety and Health
CDC Pamphlet: Quick Sleep Tips for Truck Drivers
National Sleep Foundation: Non-Medical Treatments for Shift Work Disorder