Sleep Apnea and Cancer: Is There a Link?
By Abdulrahman Al Bochi - Student
Woman sleeping in bed (Photo: Free-Photos at Pixabay)
For more than 5.4 million Canadians, a good night’s sleep is nowhere to be found. While sleep apnea can greatly sacrifice quality of sleep, the risks may go beyond feeling sleepy. A recent study investigated the effects of sleep apnea on our immune system and the impact that this may have on cancer incidence.
What is Sleep Apnea?
Sleep apnea is an obstructive sleeping disorder where sufferers stop breathing at night for up to 30 seconds at a time. When muscle tissue in the airway relaxes, it can block airflow leading to snoring or chocking. This lack of air can wake people up many times a night and greatly sacrifices quality of sleep. An estimate shows that only about 20 percent of those with sleep apnea are diagnosed with it.
How does our immune system protect us from cancerous cells?
Immunity is a complex yet ingenious system that works hard to protect us from viruses, infectious agents, and rogue cells every single day. The immune system can be separated into two main branches: the innate and adaptive immune systems. The innate system is our first line of defence that can be activated immediately or up to a few hours after a virus or infectious agent is introduced into the body.
One small yet important component of the innate system are invariant natural killer T-cells (iNKT cells). These cells can release chemicals to signal anti-cancerous responses. They also have the ability to directly kill tumour cells.
How is the immune system affected by a lack of sleep?
Researchers from a recent study investigated whether the number of circulating iNKT cells was affected in individuals with sleep apnea. They recruited 33 participants ranging from having no sleep disorders to severe sleep apnea.
The researchers collected and analyzed blood samples to determine the number of circulating iNKT cells. They found that participants with high severity of sleep apnea had a significantly lower number of circulating iNKT cells in their blood as compared to those with moderate and low sleep apnea severity.
The researchers from the same study also investigated whether exposing iNKT cells to a low oxygen environment would impact their ability to kill tumour cells. The purpose of this was to emulate the environmental conditions experienced when an individual with sleep apnea is not breathing.
They incubated iNKT cells in low and normal oxygen concentration environments for 24 hours at body temperature. iNKT cells exposed to low oxygen conditions eliminated 2757 tumour cells as compared to 3232 in cells exposed to normal oxygen conditions.
How is sleep apnea linked to cancer comorbidity?
It is widely shown that iNKT cells direct anti-tumour responses. Now, given the results of this recent study that people with sleep apnea have fewer iNKT cells and are exposed to intermittent hypoxic conditions, it raises the possibility of a link between sleep apnea and cancer.
Scientific research is the process of continually discovering and challenging prior knowledge. There is no doubt that more research is required to systematically and directly evaluate the contribution of low iNKT cell levels in individuals with sleep apnea to cancer incidence. Abdulrahman Al Bochi is a student studying biomedical sciences at Ryerson University in Toronto, Canada.