About 15 million Americans work the night shift (or third shift), clocking in around midnight and clocking out after the sun rises. In 2021, the demand for night shift workers increased as organizations tried to meet booming consumer demand and work through supply chain bottlenecks from the COVID-19 pandemic. Job search website ZipRecruiter reported that postings for jobs requiring overnight shifts were up 14 times levels 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 shifts both during the day and overnight) can come with dangerous health consequences. These may include an increased risk of developing some cancers, such as breast cancer and lung cancer.

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

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 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, 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 circadian rhythms. Specifically, artificial light exposure 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
• Peptic ulcers
• Chronic fatigue

Night shift workers may also develop lifestyle habits that may increase their risk of developing certain health conditions, including multiple myeloma. These risky behaviors may include consuming more energy drinks or caffeine, smoking, routinely using aspirin or ibuprofen, and eating an unhealthy diet, which may lead to obesity and a higher body mass index.

Night Shift Work and Myeloma

There’s not a lot of research on the connection between night shift work and multiple myeloma specifically. The research that does exist does not support a significant association between night shift work and multiple myeloma, though there may still be some risk.

For instance, some research of female nurses shows that there is a suggested relationship between night shift work and myeloma, as well as other blood cancers like certain types of leukemia and lymphoma.

The number of years a person spends working the night shift is also directly correlated with an increased risk of developing cancer. One study found higher risk for myeloma and other blood cancer subtypes when people worked more than 15 years in rotating night shift work.

With an increase in demand for night shift workers, more research and clinical trials are needed 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 non-Hodgkin lymphoma 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. 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 (safe and comfortable) 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 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:

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

These suggestions are recommended for everyone, no matter what time of day you work, but other tips are more specific to people who work the night shift. These recommendations include:

• Blocking out daytime noises with a white noise machine or earplugs
• Eating your meals at the same time each day
• Eating high-protein foods to help you stay alert
• Taking time to relax after work
• Having a light snack before going to bed
• Using blackout shades to mimic nighttime
• Avoiding sleeping pills and other medications that cause drowsiness
• If you are pregnant, working 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 consecutive night shifts that you work. This can help you to avoid the long-term health risks associated with disrupting your natural sleep cycle.

You’re Not Alone

If you have multiple myeloma, it can help to have the support of others who understand. MyMyelomaTeam is the social network for people with myeloma and their loved ones. More than 14,100 members come together to ask questions, give advice, and share their experiences with others who understand life with myeloma.

Do you think night shift work contributed to your risk of myeloma? Share your experience in the comments below, or start a discussion on MyMyelomaTeam.