More than 15 million Americans work the night shift (or third shift), putting their hours in during the middle of the night. In 2021, the demand for night shift workers increased 14 percent compared to before the COVID-19 pandemic started. Many companies and industries are trying to keep up with the labor shortages and face increased pressure to operate 24/7.

Although there are potential perks to working the night shift — increased pay, less traffic, more flexibility, and less distraction — research shows that long-term rotating shift work comes with dangerous health consequences. These may include an increased risk for developing cancer, including leukemia and lymphoma.

This article discusses why night shift work can be dangerous to your health, how third shift work may increase your chances of getting leukemia, and ways to minimize the risk if you find yourself working in the middle of the night.

How Night Shift Work Can Cause Health Risks

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, which creates a circadian disruption, as a probable 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, which can cause the body to miss critical signals that help keep the immune system strong. The artificial light someone working the night shift is exposed to is often the main culprit in disrupting the circadian rhythm. Specifically, artificial light at night decreases the production of melatonin, a hormone that is triggered during darkness to help us sleep. Another important function of melatonin is to help stop tumor growth and malignancies.

In addition to melatonin suppression, a sleep pattern imbalance can also cause the following negative health outcomes:

• Cardiovascular disease
• Obesity
• Gastrointestinal disturbances
• Anxiety
• Depression
• Diabetes
• Chronic fatigue
• Endocrine disorders

To accommodate the necessary changes associated with working against the normal sleep cycle, night shift workers also tend to develop lifestyle habits that may increase their risk of developing certain health conditions, including hematologic (blood) cancer. These risky behaviors may include:

• Consuming more energy drinks or caffeine
• Smoking
• Routinely using aspirin or ibuprofen
• Eating an unhealthy diet, which may lead to obesity and a higher body mass index (BMI)

Night Shift and Leukemia

Although research shows a strong correlation between night shift work and increased incidence of breast cancer, there is mixed and inconclusive evidence linking routine shift work to blood cancers such as leukemia. The biggest risk factor discovered was the number of years a person spends working the night shift. The risk of leukemia and other blood cancer subtypes increased in individuals with more than 15 years dedicated to a nighttime career.

With an increase in demand for night shift workers, more research and clinical trials are warranted to study the long-term outcomes 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 an effective sample to study the effects of night shift work regarding various types of cancer, including breast cancer, lung cancer, and colorectal cancer. Other research including men has examined the risk of cancers as well, including prostate cancer, with inconclusive results.

Working the night shift harms your physical and mental health, especially when you work these hours for many years. With this information, preventive measures and changes to health care and organization policies can help keep workers safe. These changes include:

• Enforcing rules that workers receive an appropriate number of breaks
• Providing healthy and ergonomic working environments
• Encouraging routine cancer screenings and follow-up for night shift workers

Minimizing Your Health Risk

Many jobs and careers that are critical to our health, safety, and convenience are run as 24/7 operations that require many of its employees 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 wind up working at night in the short term or long term.

The best ways to minimize your health risk while working the night shift include:

• Eating a healthy balanced diet
• Limiting your alcohol consumption
• Getting routine physical activity
• Minimizing caffeine and energy drink intake
• Drinking lots of water

Additionally, following are helpful tips specific to people who work the night shift— but that can be useful to anyone:

• Block out daytime noises with white noise or earplugs.
• Eat your meals at the same time each day.
• Eat high-protein foods to help you stay alert.
• Take time to relax before going to sleep.
• Have a light snack before going to bed.
• Use blackout shades to mimic nighttime.
• Avoid using sleeping pills and other medications that cause drowsiness.
• If you are pregnant, work only one night shift per week.

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 to avoid the long-term health risks associated with disrupting your natural sleep cycle.

You’re Not Alone

If you have leukemia, it can help to have the support of others who understand. By joining MyLeukemiaTeam, you gain a community of more than 9,800 people affected by leukemia. Members come together to ask questions, give advice, and share their experiences with those who understand life with leukemia.

Do you work the night shift? How many years did you spend working at night? Share your experience in the comments below, or start a discussion on MyLeukemiaTeam.