While you are asleep, you go through three different stages. Stage 1 is the simplest, when you feel like you haven’t slept at all. In this stage, your body is quiet and you can’t move your eyes. However, during this stage, your brain becomes active. This activity allows you to tune out the external world and focus on the process of regeneration. You may remember small bits and pieces of images, or experience bursts of rapid brain waves.
While you’re sleeping, your brain is changing. When you wake up, the brain is active again. During this state, you can’t remember everything that happened during the day. This is called REM sleep, because your eyes continue to move frequently. In contrast, during NREM sleep, your EEG is a lot less active. While you’re awake, your brain is still working, but it’s doing a good job regulating energy and metabolism.
While we’re awake, our brains still respond to external stimuli. Your muscles and heart rate are resting. In the middle of the night, your brain begins to slow down and your eye movements cease. The heart rate and muscle tone continue to slow down. Your brain waves occasionally spike and fall, which helps you maintain optimal emotional and social functioning while awake. When you’re asleep, your brain is more alert and responsive than when you’re awake.
REM sleep is characterized by a rapid pulsating movement of the eyelids. In REM sleep, your entire body is paralyzed, and most of your muscles relax. The total energy expenditure of the body during this stage is decreased. During non-REM sleep, most muscles relax, but the eye muscles and respiratory muscles remain active. REM sleep is also called rapid eye movement sleep, due to the darting of the eyes behind closed eyelids. During REM, brain waves show definite patterns.
While you are asleep, your brain undergoes a variety of activities. Alpha activity is absent during REM, while you are awake, and you will not feel pain. The brain is in a continuous state of deep sleep, but REM does not last for long. It is a deep sleep that lasts about two to three hours. In this stage, the heart rate will be lower than normal. You may have difficulty waking up from stage one.
During REM, the brain slows and lowers heart rate, and your body prepares for deeper sleep. REM is the most difficult phase to wake up from, as it can cause disorientation and even death. During this stage of sleep, the brain performs many vital functions, including building muscle, bone, and tissues, and repairing tissue. You’ll likely have a peaceful, productive sleep. It is an essential part of human life.