Sleep is a time of rest for our bodies after a period of intensive work. While we are sleeping, the regeneration and reconstruction of our system takes place. This is the main reason why going without sleep can have an adverse impact on our health.

Sleep is divided into two fundamental phases; rapid eye movement (REM) and non-rapid eye movement (NREM) sleep. The phase of sleep can be recognised by the movements of the eyes.
In NREM Stage 3, the brain waves become even slower. Stage 3 is that of very deep sleep, during which it is extremely difficult for the sleeper to be awakened. Deep sleep is considered as being the ‘corrective and regenerative’ stage and it is essential if we are to feel rested the following day.
During the REM phase, the eyes move rapidly and in various directions. Intensive brain activity occurs. Dreaming usually takes place during this phase. The muscles are then completely relaxed and thus a person dreaming of movement will not actually be moving. In rats, serious disruption of the REM sleep phase over the course of several weeks can bring about their death.
The efficiency of a great many of our body’s functions depends on the proper length of sleep. Too little sleep can give rise to sluggish thought processes, impede concentration and focus of attention, cause irritation and slow down reaction times.