Sleep. We all need it. But, why? How do we get to sleep? What happens when we sleep? How does lack of sleep affect us? Let's take a look at the world of ZZZs.
Sleep has five different stages. When preparing to go to sleep, you usually lie down and close your eyes. The first stage of sleep is called light sleep. This is when you may startle or have a sensation of falling. As you move into the second stage, your body relaxes, your muscles may twitch, and your eyes stop moving. As you fall deeper into sleep, your breathing slows and becomes rhythmic, and your heart rate starts to slow down. In the third and fourth stages, your brain waves slow down. When you are in a deep sleep during the third and fourth stages, you are unaware of what is going on around you. It would take a loud noise or someone shaking you to cause you to wake up. If you are awakened out of a deep sleep, you will be disoriented for a few minutes. The final stage of sleep is called REM (Rapid Eye Movement) sleep. This is when you dream. Your eyes move back and forth as you are dreaming. If you want to remember your dreams, you need to wake up while you are in REM. Otherwise, your dreams are forgotten. Once you are in REM sleep, it usually lasts about half an hour. Then your sleep pattern starts from the first stage again. During the night, you will go through the five stages of sleep many times. On average, each pattern will last about an hour and a half.
Why do you need to sleep? Though scientists are not sure, they have many ideas about why you need a good night's sleep. They believe the muscles in your body are rested and repaired during sleep. It is also during this time that scientists believe your immune system is strengthened. It may be that dreams help you with your memory. In addition, it may be your body's way of recharging your brain for the next day. One thing we do know is that when infants sleep, human growth hormone is released into the body. A baby that doesn't get enough sleep will have stunted growth. We may not know for sure, but a good night's sleep seems to be essential to our health.