A study conducted by the University of Granada found that men with prostate cancer have lower levels of melatonin than those without, regardless of their urinary symptoms and the extent and depth. aggressiveness of the tumour.

This hormone regulates circadian cycles, is produced in the absence of light and is linked to the light-dark cycle.

A study conducted by researchers from the Institute of Biohealth Research of Granada (ibs.GRANADA) of the University of Granada (UGR) found that men with prostate cancer have levels of melatonin, l sleep-inducing hormone, lower than those of men who do not suffer. this disease, regardless of their urinary symptoms and the extent and aggressiveness of the tumor in question.

This work is part of the CAPLIFE (prostate cancer and lifestyles) study (Principal Investigator: Rocío Olmedo Requena from the UGR Department of Preventive Medicine and Public Health) and has been published in the Journal of Urology. The work is part of the results of the doctoral thesis carried out by Macarena Lozano Lorca and directed by José Juan Jiménez Moleón and Rocío Olmedo Requena.

As Olmedo explains, “Circadian cycles regulate many of our bodily functions; they last about 24 hours and are regulated by melatonin levels. This hormone is produced in the absence of light and is linked to the light-dark cycle”.

The level of melatonin in the body peaks at night, although its production is affected by age (decreasing with age) and can be influenced by the seasons (lower during the spring-summer months). Light pollution can also affect melatonin levels, such as using electronic devices at night. The International Agency for Research on Cancer classifies night work as a probable carcinogen, and melatonin could be one of the factors underlying this link.

Despite the fact that we spend a third of our lives sleeping, to date little attention has been paid to this important habit and its relationship to health. Sleep studies can be carried out using multiple approaches (duration and quality of sleep; shift work, including night or rotation; level of light pollution, etc.), although the most objective measurement is through the circadian rhythm analysis based on melatonin levels at different times of the day.

To undertake the first-ever analysis of the link between melatonin levels and prostate cancer, in this study, six saliva samples per participant were collected over a 24-hour period from 40 male subjects recently diagnosed with prostate cancer. prostate and 41 men without this pathology. . This allowed the researchers to measure the variations in the level of this hormone over 24 hours, its amplitude (defined by the maximum peak of melatonin production) and acrophase (time of the maximum peak of melatonin).

A lower melatonin peak

Scientists have observed that in subjects with prostate cancer, melatonin levels were consistently lower than in those without this condition, regardless of age, season of the year , the symptoms associated with prostate cancer and the degree of disease progression. Also, the time of day it was produced was later. They concluded that in the sample studied, melatonin levels in men with prostate cancer, regardless of urinary symptoms, tumor extent and tumor aggressiveness, were always lower than those of men with prostate cancer. men without this pathology.

This study was carried out at the ibs.GRANADA Institute thanks to the collaboration between researchers from the UGR, the International Institute of Melatonin, the Urology Services of the ‘Virgen de las Nieves’ and the University Hospitals’ Clínico San Cecilio’, the Andalusian School of Public Health and the Health District of Granada-Metropolitan. In addition, some of the authors of this article are members of CIBERFES and CIBERESP (the Centers for Networking Biomedical Research on Frailty and Healthy Aging, and Epidemiology and Public Health, respectively).