Sleep is generally considered to be a rejuvenation and rehabilitation process for the entire body.
It is characterized by the complex activity of autonomic cardiovascular mechanisms, but also by relative changes in blood pressure and heart rate. It has been found that the cardiovascular system has different settings, commensurate with each cycle of the sleep process.
During non-REM phase, blood pressure and heart rate tend to decrease, while the REM phase is characterized by periods of relative hypertension and tachycardia.
• the non-REM phase of sleep is characterized by pneumonogaster predominance,
• while REM is characterized by a relative increase in sympathetic activity, as evidenced by the increased sympathetic outflow for the muscular walls of the vessels.
Factors that affect Sleep Quality
A sufficient amount of slow wave sleep can be affected by a number of factors.
⇒ Any condition that disturbs night sleep (for example, strong snoring, sleep apnea or restless legs syndrome) can reduce the duration of the slow wave phase.
⇒ Women report a lower quality of sleep than men.
⇒ Still, age may have a negative effect, since as long as we grow, the duration of deep sleep is reduced.
Sleep Benefits for High Blood Pressure & Cardiovascular Health
Previous studies have linked chronic sleep disorders with higher risk of heart disease and obesity, even with a reduced life span.
A new study, published by the Hypertension journal, concludes that the quality of night sleep is the one that can cause blood pressure risk rather than "quantity".
The goal of this study, conducted by Harvard Medical School researchers, was to examine the stages of slow sleep waves, which represent deeper sleep times, ie normal and qualitative sleep. These slow wave stages consist of about 90 to 120 minutes.
To study the effect of deep sleep on health, scientists attended 784 healthy men, who at the start of the study had no symptoms of high blood pressure. During the study of 3.5 years, men had to control their blood pressure at different times and during the sleeping of the slow waves. To achieve this, they were monitored at home by a machine. In this way, researchers found that those who had spent less time in the phase of slow waves or deep sleep were more likely to develop blood pressure.
For a "normal sleep" night, about 25% of total sleep is required to consist of the slow wave phase.
The data from this study, however, showed that those who were at high risk of developing hypertension were those who enjoyed "deep sleep" for no more than 4% of their total sleep each night. Additionally, the researchers found that these men were more likely to develop apnea during sleep.
Susan Redline, MD, MPH, Professor of Medical Health at Harvard Medical School and Doctor at the Department of Sleep and Circulation, and the author of this study, said that although the study followed only men, she believes the same results will apply and for women who fail to have enough deep sleep.
During slow sleep waves, electrical activity in the brain and the heart rate of an individual slows down, the same happens with adrenaline levels and blood pressure.
The blood pressure of the average person falls about 10 millimeters of the mercury column during the lethargy, this "splash" occurs every time someone is in the state of deep sleep. This nightly drop in blood pressure is "a good thing," said Susan Redline.
When blood pressure does not fall in the evening, it can be a risk factor for cardiovascular disease.
Susan Redline has also stated that, "When this night dive does not happen, blood pressure levels are directly affected during the day. This is because the areas of the brain responsible for sleep regulation are inextricably linked to those areas of the brain that release hormones and other mediators that affect blood pressure. When these areas of the brain do not enter the state of slow waves during nighttime sleep, they can intervene by sending various signals to the brain that can affect blood pressure throughout the day. "
A new approach on treating Hypertension
Researchers have recently discovered that people with high blood pressure have substantial anatomical disorders in their biological clocks. This finding opens the door for a new approach to treating hypertension.
A different study conducted at the Dutch Institute for Neuroscience demonstrated that the biological clock is a mechanism that is involved in lowering blood pressure. The results of the study also reported that those with poor sleep quality were twice as likely to have high blood pressure. Therefore, the researchers concluded that improving sleep for a long time can help reduce blood pressure, even with persistent hypertension.
Blood pressure is considered resistant only if one receives three or more blood pressure medications and still values are still higher than 140/90 mmHg.
The researchers concluded that people with high blood pressure were more likely to experience sleep disturbances. While poor sleep quality in patients with high blood pressure can lead to persistent hypertension.
The Role of Melatonin
The effect of melatonin on daily pressure regulation can be explained by its effects on the sympathetic nervous system.
During the non-REM sleep phase, pressure is usually reduced due to reduced activity of the sympathetic nervous system and the mutual increase of parasympathetic tone. This condition leads to a reduction in cardiac output and peripheral resistance.
Patients with a non-inferior sleep profile experienced impaired cardiovascular relaxation with altered sympathetic and parasympathetic balance, resulting in reduced nighttime sympathetic sedation and maintenance of adrenergic receptor tone during sleep.
It may even have a direct effect on the peripheral arteries, causing vasodilation and pressure reduction, as melatonin receptors have been found in the arteries and mainly the central nervous system, the pituitary gland, and the cerebral vascular system. Outside the central nervous system, melatonin binding has been demonstrated in tissues, including coronaries.