What Exactly Occurs When We Sleep?
A restful night's sleep is critical for maintaining physical and mental health, yet many people do not receive enough of it. However, what occurs to us when we sleep should be something we are all aware of.
Everyone on the earth enters a condition of unconsciousness every night, but what happens within the body. At the same time, we fall asleep, and what happens if we don't get enough sleep is a subject of investigation. Rest is controlled by your circadian rhythm, a biological clock situated in the brain. As a result, the body clock reacts to light by increasing the synthesis of the hormone melatonin at night and decreasing it when it detects daylight. The body goes through four phases of sleep in cycles during the night, described here.
Every four or five hours on a good night, we go through these phases again. Stages one and two are characterized by light sleep. This is a transitional period between being awake and going to sleep. Body temperature drops, and muscles may twitch due to the slowing of the heart rate and respiration. This stage of sleep is referred to as Delta sleep in certain circles because of the slow Delta brainwaves emitted during this period. As our cells create the most growth hormone to support bones and muscles during this initial deep sleep stage, the body can heal itself and rebuild its energy reserves. Stage 4 is the point at which we begin to daydream. The body produces hormones that cause it to become momentarily paralyzed, preventing us from acting out our fantasies. When we are in this stage, our brains are incredibly busy, and our eyes, even if they are closed, move back and forth as if we were awake. Humans spend around one-third of their lives sleeping. People are sleeping far less than they were a century ago, owing to modern lifestyles, stress, and the spread of technology. Shorter periods of sleep each day (less than seven hours per day) are related to an increased risk of acquiring chronic illnesses, which may shorten one's life span.
What happens when we sleep? | The Economist