Waking up to an alarm clock triggered a spike in blood pressure
Forced awakening by an alarm clock or smartphone is not only stressful, but also leads to a spike in blood pressure as the person quickly moves from sleep to wakefulness. This acts as a risk factor for unfavorable cardiovascular conditions like stroke and heart attack.
Most modern people use alarm clocks: it is estimated that about 80% of adults wake up to them (although 57% prefer to stay in bed until the second and third rings). The first such device appeared in ancient Greece and belonged to Plato, an Athenian philosopher who lived in the fourth to fifth centuries BC and was one of the most influential philosophers in history.
It is believed that the founder of the Academy was dissatisfied with the constant lateness of students, so he designed an "alarm clock" of two chambers with adjustable water level. It rose, overflowed from one vessel into the other, compressed the air, it burst through the fuse into the flute, eventually sounded a sharp sound resembling the whistle of a kettle with boiling water.
Since then, the alarm clock has taken various modifications, and the author of the first patented invention in 1847 was Frenchman Antoine Radier. Some also invoke the name of Levi Hutchins, an American clockmaker who lived in the 18th century. But his alarm clock could not be set to a convenient time: it rang daily exclusively at four in the morning.
At various times, scientists have stated that waking up to an alarm clock does not bode well for health: its sound can disrupt the sleep-wake cycle, trigger the body's "hit or run" stress response, and cause feelings of irritability and anxiety. Yeonsu Kim, a doctoral student at the University of Virginia School of Nursing (USA), recently confirmed in a small experiment that the alarm clock in the morning not only spoils the mood, but also puts you at increased risk of adverse cardiovascular events such as stroke and heart attack. The results of the study are reported on the university's website.
Thirty-two people participated in the two-day experiment. While sleeping, they wore smart watches and blood pressure cuffs. After the first night, the subjects had to wake up without an alarm clock, naturally, and on the second night the sound signal raised them after five hours of night rest.
The author of the study then compared morning blood pressure readings after waking up. As it turned out, people who had to jump up on the alarm clock, there was a rise in blood pressure: its level was 74% higher than in the participants who woke up on their own. Because of this, Kim said, adults with cardiovascular disease may experience more harm from such a large increase in blood pressure levels when they are awakened by a sudden sharp signal.
"When the morning blood pressure spike is excessive, it can activate the sympathetic nervous system causing a "hit or run" response, which puts a strain on the heart, which starts pumping blood harder. This can lead to fatigue, shortness of breath, anxiety, stiffness (overstretching) of the neck muscles, and, in acute form, nosebleeds and headaches," the scientist noted.
In addition, the results showed that participants who got less than seven hours of rest at night were more likely to experience a severe morning spike in blood pressure. Thus, they may be at an increased risk of stroke or heart attack due to increased sympathetic nervous system activity.
While Kim's findings are yet to be cross-checked in larger studies, they pointed to the need to use different strategies and wearable devices to help identify sleep stages, wake up "gently" and offset the risks of high blood pressure.