What is Cancer?
Cancer is an illness caused by the uncontrolled division of cells. These cells form a clump known as a tumor. Cancerous tumors are categorised as benign by its ability to spread to other parts of the body.
Cancer is caused by mutations (changes) in the DNA of the affected cells. This can be due to carcinogens (which are substances that can promote mutations), viruses, or purely by chance.
Cell division is a normal process that helps in growth, repair, and immune response. In normal cells, the DNA codes for proteins that control when and how the cell divides. However, in cancer cells, that DNA is changed or removed, so these proteins cannot be made. This causes the cells to divide uncontrollably.
There are a variety of cancers, each with its own symptoms that are unique to them. However, many people find cancer by going to their doctor to check:
- unexplained weight loss.
- a lump.
- a mole that is uneven or is changing shape.1
Can Cancer Cause Insomnia?
Insomnia is difficulty in falling or staying asleep. Many cancer sufferers report insomnia, and there are a variety of reasons for this:
- Anxiety – Cancer can be a very stressful and scary condition and many people have sleep disruptions for years after recovering.
- Schedule changes – Cancer is life-changing and thus, patients have disruptions to their daily routine.
- Treatment – The side effects of some treatments can cause insomnia.
- Medication – Some of the medications used to treat cancer can cause sleeping difficulties.2
Insomnia as a Side-Effect of Cancer
As mentioned above, cancer can cause many sufferers and survivors to have insomnia. This could suggest that insomnia is almost a side-effect of cancer and its treatments.
Furthermore, it has been suggested that changes in the body’s function due to cancer can change the response of neural circuits (the pathways that nerves take).3 This can cause changes to sleep rhythms. However, as this area of research has only recently emerged, the exact mechanisms and chemicals involved are not yet known. However, with advancing techniques, there may be more answers soon.
Sleep is Important for the Anti-Tumor Functions of Immune Cells
Sleep is essential for the normal growth, repair, and function of our bodies. Current guidance suggests that seven to nine hours of sleep every night is ideal, however, as we are all different, this may vary slightly for some.
The immune system destroys thousands of cancerous cells every day.4 This is done by the T-cells of the immune system, which can look out for cells that could potentially progress to cancers. The T-cells are then able to destroy these cells before any damage is done.
However, a study has shown that chronic sleep deprivation can reduce the ability of the T-cells to find and destroy cancerous cells. Furthermore, sleep deprivation may also allow further growth of cells, which can progress and become malignant, resulting in cancer development.5
The same study also suggested that people with cancer who suffer from sleep deprivation are more likely to have a worse prognosis. This is because fewer T-cells are present near the tumor.5
One study, consisting of 23,620 participants, found that sleeping for less than six hours a night can increase the risk of developing illnesses such as cancer.6 This study was based on the incidence of illnesses like cancer in groups with varying amounts of sleep.
Another study was performed on sleep-deprived rats.7 This study had some interesting findings:
- DNA damage was found at a higher rate in sleep-deprived rats
- Cell death was increased in sleep-deprived rats
- Cell division was increased in sleep-deprived rats
These findings are important as cancer is caused by DNA damage and uncontrolled cell division. Thus, this study suggests that less sleep is associated with an increased risk of cancer.
When combined, these studies show that sleep is important for both preventing cancer and recovering from it.
Overall, studies have shown how important sleep is for, firstly preventing cancer, secondly recovering from it. Quality and quantity are both important, however, quantity is usually the focus of such studies as it is easier to measure.
Unfortunately, current remedies for insomnia do not always work, and hopefully, as evidence in this field grows and more research is done, there will be further research into potential cures for sleep deprivation.
- Cancer - Signs, and symptoms [Internet]. NHS.UK. 2022 [cited 24 September 2022]. Available from: https://www.nhs.uk/conditions/cancer/symptoms/
- Sleep Problems in People with Cancer - Side Effects [Internet]. National Cancer Institute. 2022 [cited 24 September 2022]. Available from: https://www.cancer.gov/about-cancer/treatment/side-effects/sleep-problems
- William H. Walker II, Borniger JC. Molecular mechanisms of cancer-induced sleep disruption. International Journal of Molecular Sciences [Internet]. 2019 Jun [cited 2022 Oct 20];20(11). Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6600154/
- Staff C. How does the immune system work? [Internet]. Cancer Research Institute. 2022 [cited 30 September 2022]. Available from: https://www.cancerresearch.org/en-us/blog/april-2019/how-does-the-immune-system-work-cancer
- Huang J, Song P, Hang K, Chen Z, Zhu Z, Zhang Y, et al. Sleep deprivation disturbs immune surveillance and promotes the progression of hepatocellular carcinoma. Front Immunol [Internet]. 2021 Sep 3 [cited 2022 Oct 20];12:727959. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8446513/
- von Ruesten A, Weikert C, Fietze I, Boeing H. Association of sleep duration with chronic diseases in the European prospective investigation into cancer and nutrition (Epic)-Potsdam study. PLoS One [Internet]. 2012 Jan 25 [cited 2022 Oct 20];7(1):e30972. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3266295/
- Everson CA, Henchen CJ, Szabo A, Hogg N. Cell injury and repair resulting from sleep loss and sleep recovery in laboratory rats. Sleep [Internet]. 2014 Dec 1 [cited 2022 Oct 20];37(12):1929–40. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4548518/