About 15 million Americans work the night shift (or third shift), clocking in around midnight and leaving after the sun rises. In 2021, the demand for night shift workers increased substantially as organizations tried to meet booming consumer demand and work through the supply-chain bottlenecks introduced by the COVID-19 pandemic. Job search website ZipRecruiter reported 14 times more job postings for overnight shifts than there’d been before the pandemic.
Although there are potential perks to working the night shift — higher pay, less traffic, more flexibility, and less distraction — research shows that long-term rotating shift work (working both shifts during the day and overnight) comes with dangerous health consequences. These may include an increased risk for developing cancer, including lymphoma.
This article discusses why night shift work can be dangerous to your health, how third shift work may increase your chances of developing lymphoma, and ways to minimize the risk if you find yourself working the night shift.
The most dangerous aspect of night shift work is the disruption it has on sleep schedules and the circadian rhythm. In 2007, the International Agency for Research on Cancer declared shift work that involves a circadian disruption as a probable human carcinogen (cancer-causing agent).
A normal sleep pattern includes sleeping when the sun is down and being active when the sun is up. However, during night shift work, this pattern is reversed. This reversal can cause the body to miss critical signals that help keep the immune system strong.
During night shift work, a person may be exposed to artificial light, which is often the main culprit in disrupting circadian rhythms. Specifically, nighttime exposure to artificial light decreases the production of melatonin, a hormone that is triggered during darkness to help us sleep. Among melatonin’s important functions, it helps stop tumor growth and malignancies.
In addition to suppressing melatonin production, a sleep-pattern imbalance can cause the following negative health outcomes:
Night shift workers also tend to develop lifestyle habits that may increase their risk of developing certain health conditions, including lymphoma. These risky behaviors may include:
Although research shows a strong correlation between night shift work and increased risk of certain cancers such as breast cancer, there is inconclusive evidence linking routine shift work to blood cancers such as lymphoma.
Studies have shown that, compared to women, men working the night shift have an increased risk of developing non-Hodgkin lymphoma (NHL). This risk difference may be linked to the hormone estrogen and its role in cell division and the circadian rhythm process.
The number of years a person spends working the night shift is also directly correlated with an increased risk of developing cancer. A person’s risk of lymphoma and other blood cancer subtypes increases when they’ve spent more than 15 years in a nighttime career.
With an increase in demand for night shift workers, more research and clinical trials are needed to study the long-term effects of working during the night, especially when it comes to cancer risk and its implications for public health. Research has commonly used female nurses working the night shift as a sample to study the effects of night shift work on different types of cancer, including breast cancer, lung cancer, and colorectal cancer. Other research including men has examined cancer risk, including NHL and prostate cancer, with inconclusive results.
Working the night shift can harm your physical and mental health, especially when you work these hours for many years. Preventive measures and changes to company policies can help keep workers safe. These changes include:
Many jobs and careers that are critical to our health, safety, and convenience are for 24/7 operations that require people to work the night shift. Although the dangers of mixing up your sleep schedule and circadian clock are well known, these shifts are not going away. It is important to take steps to protect your health if you work at night, either in the short term or long term.
The best ways to protect your health include:
These suggestions are recommended for everyone, no matter what time of day you work. There are also helpful tips specific to people who work the night shift. These recommendations include:
If you enjoy working the night shift, or if your career demands it, try to limit the number of years and number of consecutive shifts that you work. This can help you to avoid the long-term health risks associated with disrupting your natural sleep cycle.
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Do you think night shift work contributed to your risk of lymphoma? Share your experience in the comments below, or start a discussion on MyLymphomaTeam.