Science has discovered a new life-style issue that can slow down the progress of cancer: sleep melatonin!

We’ve known for a long time that getting a good night’s sleep – good enough that you don’t need an alarm clock to wake you up – is linked to better health: less diabetes, lower blood pressure, a lower risk of heart attack. Recently, several international research groups have discovered that sleeping also protects you from cancer.
One large Japonese study looked at 24,000 women over the course of eight years. For women who slept less than six hours a night, the risk of cancer rose 60% -- roughly equivalent to the increase in risk linked to post-menopause hormone replacement therapy — compared to those who slept at least seven hours. Those who slept nine hours a night were protected against breast cancer (their risk of developing the disease dropped by 28 percent). [1]
In another study, this time in the US, the protection against cancer conferred by moderate physical exercise (30 minutes or equivalent of rapid walking, six days a week) almost completely disappeared in people who slept less than seven hours a night. [2]
During sleep, and in appropriate condiitions of darkness, the brain continuously secretes a little hormone called melatonin. Exposure to the light (even for less than a minute) cancels this secretion. At the Basset Research Institute in New York state, Dr. David Blask has shown that melatonin acts directly on cancer cells, reducing their growth. Melatonin also reduces the cancer cells’ assimilation of omega-6 fatty acids (which increases inflammation in the tumor, and its growth). [3 , 4]
At the San Gerardo hospital in Milan, Italy, a research team headed by Prof. Lissoni has been studying the effects of melatonin in the treatment of cancer for over twenty years. Their work has shown that, for several different types of solid tumors in an advanced stage (breast, lung, cancers of the head and neck, glioblastomas), treatment by chemotherapy or radiotherapy often achieved much better results if patients also received 20 mg of melatonin when going to sleep in the evening. In addition, patients receiving melatonin had fewer problems with side-effects (thrombocytopenia, neuropathic conditions, coronary problems, bleeding from the gums and profound fatigue). [5 , 6]

For people, like me, who have a strong tendency to feel guilty when we spend too long in bed, it does you good just to remind yourself that sleep is not a luxury or laziness – it’s a fundamental function to restore our body.


1.    Kakizaki, M., et al., Sleep duration and the risk of breast cancer: The Ohsaki Cohort Stud. British Journal of Cancer, 2008. 99: p. 1502-1505.

2.    McClain, J.J., et al., Association between physical activity, sleep duration, and cancer risk among women in Washington County, MD: A prospective cohort study, in American Association for Cancer Research -  Seventh Annual Conference on Frontiers in Cancer Prevention Research. 2008: Washington, DC. p. 157 - Abstract B145.

3.    Blask, D.E., et al., Light during darkness, melatonin suppression and cancer progression. Neuro Endocrinol Lett, 2002. 23: p. 52-6.

4.    Blask, D.E., S. Wilson, and F. Zalatan, Physiological melatonin inhibition of human breast cancer cell growth in vitro: evidence for a glutathione-mediated pathway. Cancer Research, 1997. 57: p. 1909-1914.

5.    Lissoni, P., et al., Decreased toxicity and increased efficacy of cancer chemotherapy using the pineal hormone melatonin in metastatic solid tumour patients with poor clinical status. European Journal of Cancer, 1999. 35(12): p. 1688-92.

6.    Lissoni, P., et al., Increased survival time in brain glioblastomas by a radioneuroendocrine strategy with radiotherapy plus melatonin compared to radiotherapy alone. Oncology, 1996. 53(1): p. 43-6.