Surreal image representing circadian rhythm disruption due to night shift work.

Night Shift Work: Are You at Risk for Cancer?

Kai Mendoza in Health & Wellness December 2025 • 4 min read.

"Uncover the surprising link between working the night shift and increased cancer risks, and learn what you can do to protect your health."

In today's 24/7 world, many people work during the night, especially in healthcare and other essential services. While night shift work keeps society running, it can disrupt the body's natural sleep-wake cycle, also known as the circadian rhythm. This disruption can have significant consequences for your health.

The circadian rhythm, controlled by a biological clock in the brain, regulates essential functions like hormone production and cell growth. When night shift work throws this rhythm off balance, it can lead to various health problems, including an increased risk of certain cancers.

This article examines the scientific evidence linking night shift work to cancer, explaining how circadian rhythm disruption affects the body and what steps you can take to minimize your risk.

How Does Night Shift Work Increase Cancer Risk?

Surreal image representing circadian rhythm disruption due to night shift work.

The disruption of the circadian rhythm is a key factor linking night shift work and cancer. This rhythm influences numerous bodily processes, including the production of melatonin, a hormone with antioxidant and oncostatic (cancer-fighting) properties. Night shift work, particularly exposure to artificial light at night, can suppress melatonin production.

Reduced melatonin levels can disrupt the delicate balance between factors that promote and inhibit cell division, potentially leading to uncontrolled cell growth and tumor development. Studies have also shown that circadian rhythm disruption can affect DNA repair mechanisms, making cells more vulnerable to damage that can lead to cancer.

Breast Cancer: Several studies have found a link between night shift work and an increased risk of breast cancer in women.
Endometrial Cancer: Research suggests that women who work night shifts for extended periods may have a higher risk of endometrial cancer.
Colorectal Cancer: Some studies have indicated a possible association between night shift work and an increased risk of colorectal cancer.
Prostate Cancer: A prospective study on Japanese workers found that night shift workers had a significantly higher risk of prostate cancer.

It's important to note that not all studies show a definitive link, and more research is needed to fully understand the connection between night shift work and cancer. However, the existing evidence suggests that circadian rhythm disruption is a plausible mechanism for this increased risk.

Protecting Your Health as a Night Shift Worker

While the research suggests an increased cancer risk for night shift workers, there are steps you can take to minimize this risk. Creating a healthy work-life balance and prioritizing sleep are crucial.

Here are some strategies that may help: <ul> <li>Optimize Your Sleep Environment: Make your bedroom dark, quiet, and cool. Use blackout curtains, earplugs, and a white noise machine if necessary.</li> <li>Maintain a Regular Sleep Schedule: Even on your days off, try to stick to a consistent sleep-wake cycle as much as possible.</li> <li>Minimize Light Exposure at Night: Use blue light-blocking glasses during your shift and dim the lights in your workspace.</li> <li>Maximize Light Exposure During the Day: When you wake up, expose yourself to bright sunlight to help regulate your circadian rhythm.</li> <li>Consider Melatonin Supplements: Talk to your doctor about whether melatonin supplements are right for you.</li> <li>Practice Good Nutrition and Exercise: Maintain a healthy diet and exercise regularly to support your overall health.</li> <li>Schedule Regular Checkups: Be sure to schedule regular checkups and cancer screenings with your doctor.</li> </ul>

By taking proactive steps to protect your circadian rhythm and overall health, you can minimize the potential risks associated with night shift work and promote your long-term well-being.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.4067/s0717-95532011000300008, Alternate LINK

Title: Trabalho Noturno Como Fator De Risco Na Carcinogênese

Subject: General Nursing

Journal: Ciencia y enfermería

Publisher: Universidad de Concepcion

Authors: Marina Izu, Elaine Antunes Cortez, Geilsa Cavalcanti Valente, Zenith Rosa Silvino

Published: 2011-12-01

Everything You Need To Know

How does working the night shift potentially raise my risk of developing cancer?

Night shift work can increase cancer risk because it disrupts the body's natural sleep-wake cycle, known as the circadian rhythm. This disruption particularly affects the production of melatonin, a hormone with antioxidant and cancer-fighting properties. When melatonin production is suppressed due to exposure to artificial light at night, it can lead to uncontrolled cell growth and make cells more vulnerable to DNA damage, increasing the likelihood of tumor development. Further research is being conducted to have a more definitive understanding of the effect of night shift work.

Are there particular types of cancer that are more common in people who work night shifts?

Studies have found associations between night shift work and increased risks of specific cancers. In women, there is evidence linking night shift work to a higher risk of breast cancer and endometrial cancer. Some studies also suggest a possible connection between night shift work and an increased risk of colorectal cancer. Additionally, a study on Japanese workers found that night shift workers had a higher risk of prostate cancer. However, it's important to remember that not all studies confirm these links, and more research is needed to fully understand these connections. Other types of cancer may be linked, but there is limited research at this time.

What steps can night shift workers take to reduce their cancer risk?

While research indicates a potential elevated cancer risk for night shift workers, several measures can be taken to minimize this risk. Prioritizing sleep and creating a healthy work-life balance are vital. Sleep during daytime hours and implement strategies to ensure quality sleep. Additional strategies may involve optimizing exposure to light and darkness, maintaining a healthy diet, and engaging in regular physical activity. More research needs to be done on the other types of strategies that can reduce the risks.

What exactly is the circadian rhythm, and how does night shift work affect it?

The circadian rhythm is a biological clock in the brain that regulates essential bodily functions, including hormone production and cell growth. Disruption of the circadian rhythm, often due to night shift work, can suppress the production of melatonin, a hormone with antioxidant and oncostatic properties. This disruption can affect DNA repair mechanisms, potentially leading to uncontrolled cell growth and increased vulnerability to DNA damage. A properly functioning circadian rhythm ensures the body operates optimally. It is impacted by light, dark and sleep schedules.

What is melatonin, and why is it important for night shift workers?

Melatonin is a hormone regulated by the circadian rhythm, known for its antioxidant and oncostatic (cancer-fighting) properties. It helps maintain a healthy balance between factors that promote and inhibit cell division. During night shift work, especially with exposure to artificial light, melatonin production can be suppressed. This reduction can disrupt the body's natural defenses against cancer development, potentially leading to uncontrolled cell growth and increased cancer risk. In normal conditions, the production of melatonin can be very beneficial.