Cancer is the term used to describe cells in the body that start uncontrolled cell division. The cells change character due to mutations in their genetic material and will subsequently spread to the surrounding tissue and then spread to other places in the body through the blood. The cancer cells inhibit the growth of the normal cells and, without treatment, cancer eventually leads to death. Today, there are many treatment methods in the medical world and the treatments are getting better all the time.


There are many forms of cancer, and the mystery of cancer is far from solved. But there is a strong suggestion that there is a connection between cancer, light and melatonin.

Cancer and light
If there were no artificial light on earth, we humans would be surrounded by darkness for an average of 12 hours every day.

Experiments conducted at Harvard University have shown that blind people, who always experience darkness, produce melatonin for 9-10 hours a night. Blind people also have a 50% lower risk of developing cancer compared to sighted people.

Due to artificial lighting, most people in the Western world are only exposed to darkness for 7-8 hours a night. This reduces the nocturnal production of melatonin to 6-7 hours.

Many different studies on both animals and humans point to a connection between artificial light and cancer. In an experimental animal experiment, tumours grew rapidly in animals raised in an environment with short nights and high artificial lighting, while tumours stopped growing or grew slowly in animals raised in an environment with long nights and less artificial lighting.

Using artificial lighting reduces the duration of melatonin production and the presence of melatonin in the blood. Studies of primitive societies, which are surrounded by longer periods of darkness, since they do not have artificial lighting, have shown a much lower incidence of cancer. There are of course other variables when comparing modern cultures to primitive cultures, but a growing body of evidence points to a link between the use of artificial lighting and increased health risks.

Melatonin is not the only substance produced in the pineal gland, which is quite complex. It has not yet been finally decided whether these other substances also play a significant role in the fight against cancer. This may be the reason why melatonin tablets do not seem to be as effective in fighting cancer cells as the body's own naturally produced melatonin.

Since it seems unlikely that in the near future we will give up electric lighting, it is especially encouraging to know that in 2002 the discovery was made that not all the light in the visible light spectrum inhibits the production of melatonin. It is the blue light in this light spectrum that causes inhibition of melatonin. You can solve the problem by blocking the blue light. You can use lighting that filters out the blue light for practical use, e.g. for reading, watching TV or when working on a computer. This was first demonstrated at the University of Toronto when subjects simulated night work while wearing special glasses that blocked all blue light. The subjects produced melatonin even though they were in brightly lit environments.

Melatonin and cancer in general
There is much evidence that melatonin has a protective effect in many cancer contexts:

Melatonin strengthens the body's immune system.

Melatonin strengthens the cells' ability to destroy themselves if they have been damaged. A damaged cell can develop into a cancer cell.

As an antioxidant, melatonin helps to protect the body's cells and tissues against free radicals, which are formed when oxygen is converted into energy in the body. The free radicals can damage the cells and contribute to the development of diseases, including cancer.

Melatonin may reduce the harmful effects of radiotherapy and chemotherapy.

Melatonin may reduce the production of oestrogen that some cancers depend on.

Melatonin and breast cancer
A large number of studies have been carried out which demonstrate a remarkable correlation between night work/shift work and various forms of cancer.

The Cancer Society in Denmark, for example, investigated whether there is an increased risk of breast cancer among women who engage in evening and night work.

The study was conducted among Danish women aged 30-54 and showed that the risk of breast cancer increased by up to 40% among women who work in the evening or at night.

This may be because people who do evening or night work produce less melatonin because they are exposed to light at night.

Similar studies are underway among men to investigate whether there is also a connection between evening and night work and prostate cancer.

Cancer and sleep glasses
If you work in the evening or at night and as a result need to sleep during the day, it may be a good idea to use sleep glasses 1-2 hours before you go to sleep. The sleep glasses can help to extend the duration of melatonin production, so that you get the normal and optimal 9-10 hours of melatonin production per day. In addition, it is crucial that you sleep in an completely dark room.

A crucial experiment was conducted by the highly experienced researchers Dr. George Brainard, who is a professor of neurology and Dr. David Blask, who is a researcher. They examined blood samples taken from women under three different conditions: during the day, when melatonin was not present in the blood - in the dark at night, when melatonin was present in the blood - and during the night, when the women had been exposed to several hours of artificial light. No melatonin was present in the blood of the last group of women. In another phase of the experiment, this blood (without melatonin) was injected into human mammary tumours that grew in laboratory rats. This resulted in the tumours growing rapidly. Injecting blood with melatonin resulted in the tumours growing slowly, and some tumours did not grow at all. Dr. Blask commented that blood containing melatonin "put tumours to sleep".

Research regarding cancer

Below are a number of summaries/abstracts of scientific trials dealing with cancer. The abstracts originate from medical records (copyright).