New findings have revealed that people who work in the night shift schedule might be at a higher risk of developing certain types of cancer. The new study has been conducted at Washington State University Health Science Spokane. Experts have done a controlled lab experiment, which has involved healthy participants, who have been kept on simulated night shifts and day shifts. The study has noted that the night shift has disrupted natural 24 hours rhythms in the activity of some genes linked to cancer. It has made volunteers working in the night shift schedule more susceptible to DNA damage. At the same time, it makes the body’s DNA repair mechanisms inapt to heal the damage. Experts have said that in the future, the findings of the study can be used to help prevent and treat cancer in people working in the night shift schedules, who are at higher risk of being diagnosed with cancer. However, there is a requirement for further studies to develop an effective therapy to treat such cancer patients. Experts have said that there are shreds of evidence available to prove that cancer is quite prevalent in people who work in the night shift condition. This is the reason, the World Health Organization’s (WHO) International Agency for Research on Cancer, has classified night shift work as a credible carcinogenic. The findings of the new study have been released in the Journal of Pineal Research. The co-corresponding author of the study, Shobhan Gaddameedhi, who is an associate professor at the North Carolina State University’s Biological Sciences Department and Center for Human Health and the Environment, has said that until now it has been uncertain why night shift work shoots up the risk of cancer.
Shobhan Gaddameedhi and other experts from Washington State University have teamed up with bioinformatics experts from the US Department of Energy’s Pacific Northwest National Laboratory (PNNL) to find out the possible link of the biological clock, the built-in mechanism of the body, which keeps people on day and night cycle. Experts have said that though we know that there is a central biological clock in the brain, every cell in the body as well carries its own built-in clock. These cellular clocks have genes, which are called clock genes, which are metrical in their expression. It shows that the activity levels of these clock genes differ with the time of the day and night. As per the report, the expressions of genes that are linked to cancer as well can be rhythmic and night schedule work might interrupt the cadency of these genes. Experts have come up with a simulated shift work experiment to test this process. They have enrolled 14 volunteers to spend seven days inside the sleep lab at the WSU Health Sciences Spokane. Half of the volunteers have been kept on simulated night shifts schedule and the other half of them have been assigned to simulated day shifts schedule. After finishing their simulated shifts, they have been put on a constant routine protocol, which is necessary to study internally produced biological rhythms in the human body regardless of any external pressure. As part of the procedure, they have been asked to stay awake for 24 hours in a semi-reclined position under constant light exposure and room temperature. They have been given the same snacks every hour. Experts have taken their blood samples every hour to keep the track of their biological rhythm.
The analyses of white blood cells, which have been extracted from the blood samples have revealed that the rhythms of various genes linked to cancer have been different in the night shift schedule. Scientists have noted that genes that are linked to DNA repair which have shown discrete beat in the day shift schedule have dropped their rhythm in the night shift schedule. They as well have found out the consequences of such alterations in the expression of cancer-related genes. As per the experts, white blood cells taken from the blood samples of volunteers who have been kept on the night shift schedule have shown a higher amount of DNA damage as compared to the white blood cells of the day shift volunteers. Scientists have exposed white blood cells taken from the blood samples of people kept on the night shift schedule to ionizing radiation at two different periods of the day. White blood cells, which have been radiated in the evening, have shown increased DNA damage in the night shift schedule as compared to the day shift schedule. It shows that white blood cells found in the bloodstream of the night shift volunteers have been highly susceptible to external damage due to radiation, which is a risk factor for DNA damage and cancer. Dr. Jason McDermott, the co-author of the study and a computational scientist at the PNNL has said that it means that night shift schedules disrupt the timings of the expression of cancer-linked genes, which reduces the ability of the body’s repair mechanisms. The senior author of the study, Hans Van Dongen has said that night shift workers are at higher risk of many health issues such as the increased risk of metabolic and heart diseases, mental health disorders, and cancer. Now, experts are going to conduct the same kind of experiment with real-world shift workers, who have been on day and night shifts for many years. Such experiments in the future will identify whether unrepaired DNA damage piles up over time among night shift workers.