Experts answered this question.
You run along a dark corridor, you are pursued by some creature, which in the end turns out to be your school enemy. Then you wake up in your own bed and realize that it was just a dream. Nightmares have a real impact on the bodies of many people: for example, there are those who wake up from bad dreams sweating and with a rapid heartbeat. Experts said that nightmares manifest themselves in different ways in the human body.
One of the most notable effects of nightmares is heart rate. Michael Breus, M.D., says bad dreams often cause heart palpitations and high blood pressure. REM sleep is the period two or three hours after the onset of sleep, during which we have nightmares and other dreams. During REM sleep, our heartbeat may be irregular. People who do not have the most pleasant dreams show symptoms of panic – increased sweating and heart palpitations.
In the brain, the amygdala is responsible for these symptoms – a kind of “fear center” where the greatest activity is observed during nightmares. Dr. Breus explained that the more emotional the dream, the more active the amygdala. This means that the body reacts to the threat in a dream in the same way as it would in reality. There is a theory that bad dreams are a kind of rehearsal for real threats that help people work out their reactions to various stressful situations.
Interestingly, when your brain recognizes your heartbeat, it becomes the culmination of bad dreams in some people. A study published in the journal NeuroImage: Clinical found that people who have frequent nightmares respond differently to their heartbeat during REM sleep. “Patients with sleep disorders had an increased amplitude of the evoked potential, which reflects the brain’s response to our heartbeat. This difference is only in REM sleep, ”the study says.
Evoked potential can be high in cases where we are overly emotional. At such times, the brain reacts to our rapid heartbeat and how it affects the body. It’s not entirely clear how exactly the feeling of a pounding heart rate can fuel nightmares, but there is definitely a connection.
Other parts of the body are also affected by bad dreams. During REM sleep, we experience a phenomenon called atony, according to Dr. Breus. It means that the tone of most of our muscles is zero. This is why we do not fall out of bed when we sleep. However, evidence from some studies suggests that active behavior is more common in bad dreams. More clearly, you are more likely to make faces or speak out loud when you have a nightmare than when you dream of marrying your favorite singer.
The nightmare for our body does not end there. In 2019, a study was published in the journal Psychophysiology that showed that during bad dreams, the activity of the autonomic nervous system is much higher than during harmless dreams. The autonomic nervous system is responsible for many of the internal processes in our body, including temperature, blood pressure, metabolism, the secretion of certain glands, and also controls other organs. Researchers believe that high levels of autonomic activity explain why we don’t sleep well due to nightmares. The Bustle claims that the body not only makes us wake up with fear, but also tells us to be alert to the whole body.
The next time you wake up from a nightmare and feel your palms tremble and your heart rate rise, consider that you are not alone. It takes time for your body to come back to calm from a state of high tension and excitement. That is why it is difficult to fall asleep after a bad sleep. But all the small changes in your body happen for a reason, so don’t worry – in the end you will fall asleep again.