Night shift workers are more likely to suffer from chronic health conditions such as nutritional and metabolic disorders, heart disease, mental problems, depression, and other mood disorders. Several studies have shown that cancer is more common among night shift workers. However, those studies were not able to explain why night shift work raises cancer risk.
A recent study has found the reason why people working on the night shift have a higher risk of developing cancer than those who work during normal daytime hours. The study was conducted in a controlled sleep laboratory at Washington State University Health Sciences Spokane.
In the study, researchers recruited 14 volunteers for a simulated shift work experiment. For three days, 7 volunteers were asked to complete a simulated night shift schedule, and 7 others completed a simulated day shift schedule. After the 3-day simulated shifts, all 14 volunteers were kept awake for 24 hours in a controlled room temperature with constant light exposure to study their internal biological rhythms.
The researchers collected blood samples of all the participants and analysed the changes in the cancer-related genes. They found that blood cells of night shift volunteers had more DNA damage compared to day shift volunteers. The researchers also exposed the blood cells to ionizing radiation to study the impact of radiation on DNA and its repair ability. They found that the blood cells of night shift participants had more DNA damage due to external radiation compared to day shift participants.
Based on the findings of the study, researchers concluded that night shifts disrupt the natural rhythmicity of some genes associated with cancer. This increases damage in the DNA of night shift workers and reduces the power of the body’s DNA repair mechanisms to deal with that damage. All these factors increase the risk of developing cancer in night shift workers.
Now, the researchers will perform the same experiment on shift workers in real-world to determine the impact of night shifts on cancer-related genes over time. If the results come similar to the findings of the current study, it can be used to prevent cancer in night shift workers. The study can also be used to develop drugs to reduce the mistiming of DNA repair processes. This can also help in optimising the timing of cancer therapy to maximize the effectiveness of the cancer drug and reduce its side effects in the patients.
The International Agency for Research on Cancer, a part of the World Health Organization, has recently classified night shift work as a probable human carcinogen.
