The lack or reduction of melatonin levels, a hormone related to sleep and rest, can be linked, in patients with Chronic Obstructive Pulmonary Disease (COPD), to an increase in coughing episodes or lack of oxygen during the night or to the development of in-hospital delirium in older adults hospitalized for long periods, according to studies carried out by specialists from the UNAM.

COPD is a preventable chronic degenerative disease that can be treated medically, characterized by pulmonary emphysema and chronic bronchitis. According to the National Institute of Statistics and Geography, in 2020 this problem was among the top ten causes of death in people who died after the age of 55. This meant the death of 21,972 people, of which the unspecified ones represent 67.8 percent of the cases.

Alberto Manuel Ángeles Castellanos, head of the Department of Anatomy of the UNAM School of Medicine and head of the study, pointed out that although melatonin has long been associated with the sleep-wake cycle, this is the first time that its effects have been analyzed in hospitalized people. For the study, the melatonin levels -in the morning and at night- of 55 patients at the Centro de Especialidades Médicas del Estado de Veracruz, who suffer from COPD, were reviewed.

In this work -which had the support of experts from the University of Veracruz and was presented in the Journal of Sleep Medicine & Disorders-, they reviewed the cases of those who, although they are usually fine during the day, at night they present crises due to shortness of breath, cough, and other situations, so they thought that the problem could be related to or affect the quality of sleep.

Ángeles Castellanos specified: "What we saw is that patients without COPD have an adequate melatonin release rate, compared to patients with the disease where melatonin was inhibited. We thought this might be because patients get up at night, turn on the light and this inhibits its release." To determine the daily rhythm of melatonin and cortisol release, the experts checked the concentration of the hormone in saliva, which was collected at four different times of the day: 07:00, 13:00, 19:00, and 01:00 hours.

With the work, they demonstrated that COPD patients have poor sleep quality and low nocturnal melatonin concentrations. Although there were reports of poor quality sleep, melatonin concentrations in these people had not been studied until now. "This is the first study to determine that sleep disturbance in COPD patients is probably a consequence of multiple factors, including nocturnal symptoms such as cough and dyspnea, and the administration of medications that promote exposure to artificial light, which induces a decrease in melatonin secretion," the research report.

Other studies have shown that melatonin suppresses the infiltration of inflammatory cells in lung tissue, reduces lung destruction and necroptosis, as well as decreases oxidative stress and dyspnea.

Against delirium

On the other hand, a study carried out four years earlier by Ángeles Castellanos revealed that 43 percent of hospitalized people develop in-hospital delirium. It is known that after three weeks in the hospital, some become irritable, want to go home, take off their serum, become aggressive or go into a depressive state. The study carried out at the Dr. Manuel Gea González General Hospital revealed that those who presented more irritability problems were older adults, who have low melatonin levels.

"Now in the COVID-19 pandemic, melatonin has been used a lot as a support in patients who are not seriously ill, as they respond better since the hormone is a tranquilizer, it reduces the inflammatory response and, in addition, it is a natural antioxidant," the expert pointed out.

Sleep hormone

Melatonin plays a fundamental role in sleep and its production indicates to the brain whether it is day or night; that is, it increases when it gets dark and decreases when it is light. The expert in Chronobiology pointed out that with age the levels of melatonin release in the blood decrease. It is released from 23:00 hours to 03:00 in the morning; it also participates as an anti-inflammatory, anti-aging (it offers protection to avoid cellular oxidation) and has been associated with the adequate response of the immune system.

The hormone also has natural history, as it begins to be released from eight or nine weeks of life, gradually increases and the highest levels occur from 17 to 30 years of age; however, it decreases significantly after 48 years of age. In places like Mexico City, with high rates of light pollution, a significant number of people -from children to older adults- usually present problems of lack of rest, because there was not an adequate release of the hormone.