Melatonin: The unsung hero of cancer prevention

Sleep is an activity that is common to all animals and is vital to our survival. Getting a good night's rest allows us to not just have a good day but it also benefits our overall health. Getting 7 hours of sleep every night is associated with good heart health, a strong immune system, reduced risk of cancer, diabetes, and heart disease. 

Recent studies have uncovered the crucial role that melatonin, our sleep hormone, plays in curbing both the incidence and growth of certain cancers. Melatonin is widely known as the hormone that induces sleepiness. It is released by the pineal gland in the brain in response to darkness and is responsible for regulating our circadian rhythm. Melatonin starts being released at the end of the day and allows us to get drowsy and eventually fall asleep. Night-time sleep disturbances can lead to disruption and eventually inhibition in the release of melatonin. The dangers of losing sleep in night shift workers are apparent in the fact they disproportionately suffer from breast, colon, prostate, and liver cancers. 

In a recent study, researchers looked at the sleep patterns of a population of patients undergoing routine colonoscopies. It was found that 50% of the patients who developed colorectal adenomas were getting less than 6 hours of sleep on average. Colorectal adenoma is a precursor to colorectal cancer.

So how is melatonin helping in curbing and reducing the risk of cancers?

Melatonin wears multiple hats when it comes to its role in cancer suppression; from acting as a free-radical scavenger to downregulating hormones that are linked to cancer.

Our cells have free radicals and other metabolites that are produced from the cell’s activities. These molecules are harmful to our DNA as they can damage it which can lead to cancer. Melatonin acts as a free-radical and metabolite scavenger hunting down these free radicals before they can damage the DNA. In case the damage has already occurred melatonin will actually assist in repairing the damaged DNA.

Studies show that melatonin can significantly limit the growth of breast tumors. It does this in a couple of different ways. Breast tumors and breast cancer are linked to increased estrogen levels in the body. Melatonin regulates estrogen levels and brings their levels down by reducing the synthesis of estrogen as well as by reducing estrogen levels in the blood. Furthermore, it has an anti-proliferative and apoptotic effect on cancer cells, limiting the growth of tumors. It was shown to induce apoptosis in vitro in breast cancer cells. Melatonin also induces apoptosis in vivo in rat mammary tumor cells. In fact, clinical trials show that melatonin is an effective adjuvant drug to all cancer therapies; it increases the efficacy of the therapies and alleviates some of the side effects associated with cancer treatment. 

10 million people are diagnosed with cancer each year with 6 million losing their lives. The crucial role of sleep and melatonin in cancer is undeniable. Cancer is a disease that can be caused by factors beyond our control. Sleep, however, is something we have power over and should be made a priority if we wish to live long and healthy lives.

Amna Qureshi