Night Shift Work: A Risk Factor for Breast Cancer?

Working at night has perks and privileges. The pay is better, traffic is lighter, and you have more time to access public services. However, before you get too comfortable with your nocturnal schedule, you should be aware of the link between night shift work and breast cancer.

The Bureau of Labor Statistics revealed that over 15 million Americans work night shifts. These laborers, including law enforcers, medical professionals, commercial drivers, customer service representatives, aircrew, and construction workers, perform their jobs outside the standard 9 AM to 5 PM schedule. The United States relies on them to provide essential public services and meet globalization demands. Unfortunately, night workers face inherent health risks. Women, in particular, raise their risk for breast cancer by working odd hours long-term.


The Ties Between Night Shift Work and Breast Cancer

In 2013, researchers investigated 1,134 women with breast cancer and 1,179 without the illness. They were of similar age and lived in Kingston, Ontario, and Vancouver, British Columbia. The women also had different occupations. They provided their personal information, including their employment history, work schedule (to determine the shift work pattern), and hospital records (to identify tumor type). Both groups had one in three women working night shifts.

The study did not find conclusive evidence that working at night for up to 14 years or between 15 and 29 years raised breast cancer risk. However, women who had been working night shifts for 30 years or more had double the risk of developing breast cancer than those who did not work graveyard shifts.


Why Working at Night May Increase Breast Cancer Risk

Working the night shift disrupts your body’s natural circadian rhythms. Your body is tuned to be awake during the day and asleep at night. The hormones that control your sleep-wake cycle, like melatonin, work on an approximate 24-hour cycle. Night shift work counters this cycle, altering hormone levels and biological processes. The longer and more often you work nights, the higher the risk. Some possibilities:

  • Less melatonin means less protection from cancer cell growth. This hormone plummets during night shift work, reducing its anticancer potential.
  • Increased exposure to artificial lights is a plausible cancer risk factor. Ideally, everyone should be fast asleep at night, but graveyard shift workers bask in artificial lighting.
  • Those with insomnia without depression have high cortisol levels, which increase further before and after nighttime work. When heightened levels of this stress hormone follow a consistent daily pattern, it may contribute to greater cancer risk. Find out more about the link between stress and breast cancer here.
  • As mentioned, working at night disrupts circadian rhythms and leads to obesity, which is one of the many risk factors for breast cancer. Individuals who brave the night shift tend to gain weight faster than their day shift counterparts. The reasons are twofold. First, they often rely on fast food for meals, as most restaurants close before midnight. These convenient meals are high in calories, fat, and carbohydrates. Second, disrupted sleep patterns impact hormones that regulate appetite and metabolism.

If you have been working nights for several years, talk to your healthcare provider about ways to reduce health risks. Breast cancer aside, night shift work also puts you at risk for heart disease and diabetes.


How Night Shift Workers Can Reduce Breast Cancer Risk

Below are tips to help lower your risk. Every precaution can make a difference in your long-term health and well-being.


1. Plan Meals and Say “No!” to Unhealthy Food Temptations

Working night shifts cause metabolic issues and cancer-causing weight gain due to disrupted sleep patterns and poor diets.

Follow consistent eating patterns and choose nutritious, easy-to-digest foods like whole wheat bread, rice, eggs, salmon, and most fruits and vegetables. Frequent light meals or healthy snacking will also help prevent drowsiness from heavy meals. Moreover, avoid sugar, deep-fried foods, and processed meals to stabilize energy levels. P.S. These unhealthy food options may contribute to breast cancer development, too. Plan your meals to avoid temptations.


2. Maintain a Consistent Sleep Schedule

Your mind and body need a minimum of 7 hours and a maximum of 9 hours of sleep to function optimally. Any less incurs “sleep debt” repaid only through catch-up sleep, but it can take several days to recover from the side effects of sleep loss.

Working nights involves managing daytime sleep to minimize debt and fatigue. However, daytime sleep is often lighter, shorter, and poorer quality due to light, noise, and temperature.

Sleep deficiency may lead to breast cancer development, especially in postmenopausal women. Try these steps to promote better sleep after a night shift:

  • Sleep in a quiet, dark, comfortable bedroom. Use earplugs, blackout curtains, and electric fans or air conditioners if necessary. 
  • Avoid caffeine, alcohol, and smoking, especially before bed. They diminish sleep quality. 
  • Avoid stimulating activities like exercising or going through social media before going to bed.
  • Remind your household members not to disturb you and to be as quiet as possible when walking past your room.


3. Control Light Exposure

As discussed, artificial light affects circadian rhythms, and timed bright light exposure can alter sleep cycles. If you already use bright lights during your shifts, avoid further exposure from your smartphone and other devices before bed to ensure quality sleep.

Related: Habits to Reduce Breast Cancer Risk


Seek Regular Breast Cancer Screenings if You Work Late Nights

Get regular mammograms starting at age 40 or 50, depending on your personal risk factors. In addition to mammograms, everyone – yes, including assigned males at birth – should perform regular breast self-exams. See a doctor right away if you notice anything suspicious. While the majority of breast changes are benign (noncancerous), it’s best to get your doctor’s professional opinion, particularly if you work nights and have other risk factors.

Also read: Ultimate Guide to Getting Screened for Breast Cancer


The Bottom Line

Ladies and gentlemen, if you’re a working night owl, ensure to take extra precautions. Staying up late or until the sun rises can have severe health consequences.

While more studies are necessary to prove a direct connection between shift work and breast cancer, sleep deficiency’s associations with cancer contributors, like poor dietary habits and obesity, already strengthen this probability.

If possible, switch to a daytime schedule or maintain good sleep hygiene on your days off at the very least. Staying up all night might seem fun and rebellious when you’re young, but as an adult, your health depends on resetting your broken internal clock.


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