Sleep is an important biological process in humans. It is such an essential process that without it we cannot function properly. Biologists, doctors, psychologists, physicians, chemists, and even gym trainers recommend seven to nine hours of sleep, from which we can all assess the importance of sleep. But if sleep is good, a person feels fresh all day long, and if sleep is not good, a person feels sleepy all day long and feels strangely tired. In today's post, we will see how many stages of sleep there are in total, how long each stage lasts, and which stage is the one in which we feel very fresh when we wake up, and in which stage do we feel sleepy when we wake up. Basically, sleep is divided into two types, and they are called non-rapid eye movement and rapid eye movement. Non-rapid eye movement is a stage that consists of three more stages, which are called one, two, and three respectively. This is the stage in which our eyes do not move rapidly while sleeping and is also called a stage of sleep in which we keep crossing the moment from sleep to deep sleep. The second stage of sleep is called rapid eye movement. This is a very stage of sleep, which is called deep sleep, and at the end of it, if we wake up, we feel very refreshed. The stage of non-rapid eye movement is further divided into three stages. The first of these are called E1, E2 and E3. The lightest of them is E1 and according to some data, its duration is up to 10 minutes and according to some data, its duration is up to 20 minutes and 30 minutes. This depends on the mental health, physical health, psychology and fatigue of the person. By the way, to know the duration of time with more accuracy, you can do a simple Google search. Now let's talk about N2, its duration can be up to about 40 minutes, while N3 lasts for one to one and a half hours. Now, if a person wakes up in N1 stage, that is, in the initial state of sleep, he feels a little sleepy and if that person wakes up in N2 stage, he will feel a little more sleepy. But N3 stage is a stage that is called deep sleep. In this, if a person is woken up, for a few moments he sees his surroundings blinking repeatedly and is not even able to walk properly. While if we talk about the rapid eye movement stage, it is a deeper than deep sleep in which our sleep starts to break, that is, it is a transitional stage in which we start to wake up from sleep slowly and at the same time we start to leave deep sleep, that is, it is a transitional stage and if at the end of it a person is woken up or he wakes up himself, he feels very fresh.