Despite the common belief that there is one single criterion for the definition of sleep, there are actually several. These include physiological, motor, sensory, and behavioral criteria. Some of these criteria are absent or insufficient during sleepwalking or wakefulness. However, when several observers are in agreement, it is usually easy to differentiate between sleep and wakefulness. However, if there is disagreement, sleepwalkers are often mistaken for asleep individuals.
Many scientific studies show that sleep plays an essential role in our body. Our immune system depends on sleep. Depriving our bodies of sleep can suppress this response, leaving us susceptible to germs and other illnesses. During sleep, our body releases specific proteins, or cytokines, which help us fight infection. Studies show that sleep can help with heart health. In addition to helping us recover from illness and stress, sleep also contributes to our memory.
REM sleep occurs 90 minutes after we fall asleep. During this time, brain waves show slow patterns. Eye movements are also rapid. Our heart rate is also elevated. During this time, most people dream. REM sleep is essential for learning and memory consolidation, as it is when the body processes information. Those who have experienced REM sleep have a better memory. However, older people tend to spend less time in this stage of sleep. They should prioritize the benefits of non-REM sleep and ensure that their daily schedules include a combination of both.
The stages of sleep also play important roles in our health. Scientists have learned that our brains actually do a lot of work during our sleep. We use these processes to process information and improve our overall health. This is the quickest way to fall asleep and feel refreshed. For the most part, sleep occurs during REM sleep, although REM sleep lasts for longer than other types of sleep. A deep stage of sleep is the hardest to wake up from because your muscles and heartbeat are regulated and your mind has the opportunity to rest.
Despite the many benefits of sleep, people who do not get enough of it are at an increased risk for developing serious health problems. Sleep accounts for one-third of the human lifespan, and is as vital to our health as food and water. Sleep helps form pathways in our brains, maintain memory, and improve concentration. However, it is difficult to predict how long someone will have in a given night. And, if you do not get enough rest, you’re less likely to be alert and respond as quickly as you would otherwise.
In animals, sleep is a natural process that involves the relaxation of skeletal muscles and an absence of goal-directed behavior. Its characteristic posture, a horizontal repose, is typical of sleep in humans and other animals. Interestingly, this passive posture is also found in marine mammals. In this way, researchers may be able to determine which structures play specific roles during sleep. But sleepwalking is difficult for animals that do not meet the criteria for the definition of sleep.