By José Tadeu Arantes
Agência FAPESP – Sleep is a fantastic research laboratory that is still relatively unexploited by science. Alternating with wakefulness, sleep occurs in cycles, accompanied by intense chemical and biological activity, not to mention reverberating emotion states.
“There’s nothing more important to human homeostasis than sleep,” says Sergio Tufik, coordinator of the Sleep Institute at the Federal University of São Paulo (UNIFESP), referring to the body’s mechanisms for self-regulation and internal stabilization. “Sleep deprivation is a very serious condition that affects all the body’s functions and even alters brain function.”
The Sleep Institute, one of the Research, Innovation and Dissemination Centers (RIDCs) funded by FAPESP from 2000 to 2013, has conducted studies that have identified, for example, the relationship between breathing disturbances during sleep and circulatory and cardiac problems, as well as the relationship between poor sleep and hormonal dysfunction.
The institute has also made polysomnographic (PSG) exams available to the public. These exams, which are conducted while patients sleep, monitor various indicators of good- or poor-quality sleep and its impact on health. The institute’s studies on sleep disturbances and working conditions have contributed to recommendations regarding the need for rest in certain occupations – for example, bus drivers. Thanks to the institute, sleep disorders have now been included on the list of conditions covered by the National Healthcare System (SUS).
Studies related to sleep disturbances gained increasing relevance on the global research agenda when sleep deprivation became a “chronic fixture” of modern society: biological rhythms were no longer following circadian cycles. “Before, the sun would come up, thereby blocking the melatonin that makes people sleepy. With artificial lighting, everything changed. People can work and enjoy themselves at night, not to mention watch television and use the Internet and all the other resources available. Modern times have made it so that people sleep less,” Tufik reasons.
The first organization devoted to the study of diseases related to sleep appeared in the United States in 1979. Several years later, studies began at UNIFESP and research accelerated in 2000 when the Sleep Institute became part of the RIDC Program funded by FAPESP.
Over the past 12 years, researchers have investigated the two-way correlation between sleep quality and the range of illnesses caused by sleepless nights or nights slept poorly. Cardiac alterations, immunological problems, psoriasis, erectile dysfunction and even cancer have been some of the reported conditions.
It was discovered, for example, that obstructive sleep apnea (OSA) – a condition that involves a pause in breathing for more than 10 seconds – may cause functional and structural changes in the heart.
Using 3D echocardiography, researchers have determined that when a person tries to breathe and the air does not go in, there is negative pressure within the thorax that reduces the amount of blood from the lungs returned to the right side of the heart, thereby preventing it from filling completely and forcing the left atrium to contract further.
“This cardiac weightlifting alters the structure of the left atrium, to the point that it reduces the volume of pumped blood,” explains Dalva Poyares, who led the study that involved 56 patients diagnosed with sleep apnea, published in the journal Heart in late 2009. “Besides being an obstruction of the throat, apnea can affect the entire circulatory system and cause mechanical problems in the heart. If left untreated, these tend to become permanent, and over time, can even lead to cardiac insufficiency,” the researcher adds.
The research mentioned was part of a larger study titled, “Cardiovascular risk stratification in patients with sleep apnea,” which evaluated more than 600 people. “Ten articles were published as a result of the study,” reports Poyares.
Obstructive sleep apnea mainly affects middle-aged men. It is characterized by intense snoring and pauses in breathing (apneas) that lead to the breakdown of oxygenation and to fragmented sleep. While the symptoms are not generally perceived while sleeping, throughout the day, patients experience tiredness/fatigue, drowsiness and cognitive impairment.
Other studies conducted at the Sleep Institute enabled researchers to correlate OSA with the metabolic syndrome that mainly affects the obese, principally those with abdominal obesity, reports Sônia Maria Togeiro, a Sleep Institute researcher and professor.
The definition of metabolic syndrome requires the presence of at least three of the following components: abdominal adiposity, pre-diabetes or diabetes, dyslipidemia (increase in cholesterol or triglycerides) and high blood pressure. “In our studies, we’ve determined that the more severe the obstructive sleep apnea in the study group, the larger the number of individuals who have the metabolic syndrome and who have more syndrome components,” says Togeiro.
In an epidemiological study involving 1,042 metabolic syndrome patients from the city of São Paulo, researchers determined that the presence of OSA increased the risk of pre-diabetes and diabetes, regardless of obesity and other known factors. “We evaluated the effect of treating OSA with a device that prevents the pharynx from closing and found it reverses the apnea. We measured the level of cortisol (a hormone related to stress) and the inflammatory substances associated with cardiovascular risk, and we achieved a reduction of these factors,” says the researcher.
“Our research suggests that obstructive sleep apnea could aggravate the metabolic syndrome and increase the metabolic and cardiovascular risk, but we still need to conduct cohort studies (in other words, long-term follow-up) to confirm these findings,” she concludes.
Togeiro says that there are current proposals calling for the definition of metabolic syndrome to include obstructive sleep apnea. Therefore, in diagnosing metabolic syndrome, the physician would also be aware of the possible occurrence of another disease, OSA, which is part of the same spectrum. In the meantime, the concern that an episode of apnea, in and of itself, could lead to death is unfounded.
“The condition is reversed after a short time interval because there is a chemical signal governed by oxygen (O2) and carbon dioxide (CO2) that notifies the brain of respiratory insufficiency. Then, the brain sends a command that sets off a ‘micro-alarm’ allowing the person to resume normal breathing,” explains Poyares.
However, because of the harmful effects of the apnea, a device known as CPAP has been developed, which when connected to a mask, pumps air into the nose during sleep, regulating the breathing of individuals who suffer from this condition.
Eight hundred physicians specialize in sleep medicine
The Sleep Institute is located in a 15-floor aluminum and glass façade building in Vila Mariana, São Paulo. “Today, we have the biggest and best sleep institute in the world,” Tufik emphasizes. With 74 beds in its main unit and 10 beds in an auxiliary unit, all equipped with PSG devices, the Sleep Institute has the capacity to conduct 100 exams per day and has already treated 170,000 patients since it was founded in 1992.
On the educational front, the institute has provided specialization in sleep medicine to 800 physicians and has trained 1,018 technicians and 94 polysomnographic analysts, in addition to 18 dentists (who make devices for controlling apnea). “These 800 physicians are now installed in 700 laboratories all over Brazil,” Tufik explains.
Tufik is proud to have been able to place polysomnography and sleep treatment on the National Healthcare System (SUS) list of approved procedures. He is also proud of the variety of equipment that was designed at the institute, including a bracelet that can determine if an individual is sleeping or awake (important for preventing cases of drowsiness while driving) and a scale that measures balance and detects how sleep-deprived a person is.
The institute has also contributed to the dissemination of information about sleep apnea and the harmful effects of snoring. “By means of a strong media outreach (the Globo Repórter program alone featured us 15 times), we’ve let the public know that snoring is really bad; it reduces the oxygen content in the blood, causes hypertension and may even lead to heart attack. All of this was not known.”
To learn more: Hormonal oscillations and Sleep and sexuality.