Well folks, it looks like there’s some concerning news out there for all you hardworking night shift workers. The National Toxicology Program (NTP) released a report on the link between persistent night shift work and cancer risk in 2021. This follows a similar report from the International Agency for Research on Cancer (IARC) that came out in 2019. Both of these organizations reviewed a variety of studies on night shift work and cancer, and both concluded that there is a strong likelihood that persistent night shift work that causes circadian disruption can lead to human cancer.
Now, you might be wondering, what in the world is circadian disruption and how does it relate to cancer? Let me break it down for you. Our bodies have a number of biological systems that follow daily patterns, or “circadian rhythms”. These systems include our sleep and wake cycle, our appetites and digestive patterns, our body temperatures, and even our moods. These rhythms are controlled by circadian clock genes that are found in nearly every cell in our bodies. The timing of these rhythms is heavily influenced by light, with light stimulating areas of the brain to keep us awake, active, and hungry. When it gets dark, our brain secretes the hormone melatonin to promote sleep.
When our sleep patterns or light/dark cues are severely disrupted, like with night shift work or traveling across multiple time zones, it can cause what’s known as “circadian disruption”. This means that our circadian rhythms are not working together, which can lead to poor health and an increased risk of illness and accidents.
Circadian disruption can also harm biological systems that help prevent cancer. For example, melatonin can help stop tumor growth and protect against the spread of cancer cells. Studies on laboratory animals have shown that exposure to light at night can lead to the growth of breast or mammary-gland cancer. Studies on nurses and other night shift workers have also shown an increased risk of breast cancer.
So, what does this mean for night shift workers? It looks like people who regularly work night shifts appear to be at the highest risk, especially if they work:
- Night shifts of at least 3 hours between midnight and 5:00 AM
- Frequent night shifts (3 or more nights per week)
- Long-term night shift work (10 or more years)
- Night shift work that began in early adulthood (such as before the age of 30)
There are also other factors that are more common among night shift workers that may contribute to the risk of cancer, such as workplace and social stressors, poor lifestyle habits, decreased exposure to sunlight and lower levels of vitamin D.
Night shift work has also been linked to a variety of other health problems, including type 2 diabetes, heart disease, stroke, sleep disorders, and more. Night shift workers may also be at an increased risk for reproductive issues, digestive problems, and psychological issues like stress and depression. The fatigue associated with night shift work can also lead to accidents and industrial disasters.
So, what can night shift workers do to stay healthy? Well, there are a number of things you can do. First, you can take a NIOSH online training program on shift work to learn about strategies to better cope with working at night. You should also get regular health check-ups and let your doctor know if you’re experiencing any symptoms related to night shift work, like severe fatigue or sleepiness, trouble sleeping, irritability, poor performance, unexplained weight changes, and more. You can also practice good health habits to combat the effects of night shift work, like getting enough sleep, eating a nutritious diet, exercising regularly, avoiding tobacco, and limiting alcohol consumption.
References:
