Many people think that when you sleep, you just have dreams, but sleep is the best healer and an essential part of your body. Every human being have something called the sleep/wake cycle that lasts around 90-110 minutes and restarts. A sleep wake cycle is the act of falling asleep and waking up. During this cycle, there are two major stages called REM and NREM. REM stands for rapid eye movement which is the dreaming part of sleep where the brain is more active. REM is where the body tries to make sense of certain emotions, and without it, people would be very moody. NREM stands for non-rapid eye movement which is when the body repairs tissues, fights harmful bacteria and germs, and restores your energy. NREM actually divides up into 4 different stages which we'll go into specifics later. As you grow older the body focuses more on NREM than REM. Different age groups need a certain amount of sleep. Teens would need around around 9 1/2 - 10 hours of sleep. In that time, lets say that an average teen spends around 80% in NREM and the rest in REM.
In a sleep cycle, there are 4 stages and then REM. The four stages are what make up NREM. Whenever you sleep, your part of the brain called the pineal gland releases this chemical called melatonin. This prepares you for sleep.The first stage is a light sleep, and in this period, the body can be easily awoken. The body's activity slows. Then, in stage 2, eye movement has stopped and brainwaves slow down with an occasional burst. As stage 2 progresses, rapid waves called "sleep spindles" starts. Next, in stage 3, a mix of sluggish brainwaves called delta waves and quick brainwaves start. After that, stage 4 consists solely on delta waves. In this stage, children's bodies release hormones for the cells.Both stages 3 and 4 are referred to as delta sleep (deep sleep). Finally, REM starts where the eye jerks around while limbs are paralyzed, and the breathing will start to become irregular. Brain waves quicken and becomes more similar to the ones you have when your awake. Heart rate and blood pressure start to increase, and your body loses some ability to control your temperature.REM where dreaming starts happening. Few people remember their dreams, and those who do, most of them can't remember it vividly. As REM finishes, the cycle repeats until the person is awake. A full sleep cycle takes around 90-110 minutes.