Sleep (from the Latin somnus ) is called various aspects of sleep, the state, the desire or the act of it, and as well as the activity or product of this that is carried out when sleeping. Sleep supposes the reversible suspension of sensory and motor interactions with the external environment, being a true requirement of the normal being.
Sleep is a state of relative inertia and impassivity that has restorative functions. It is the period when the activities and concerns of life are absent from consciousness, and the body and mind are submerged in a state of tranquility, after which they wake up recovered and strengthened to restart their daily duties.
The high and low temperatures of the human body suggest that physiologically the most appropriate time to sleep is when the metabolism drops, and the body and mind begin to fatigue. Hormonal changes also emerge that night is the appropriate time for humans to sleep.
The amount of time each human being should sleep is a personal matter. Many live well on 7-8 hours of sleep a night, but few can do well on 3-4 hours, while others need more than 8. Research has shown that those who sleep 7-8 hours live longer and they are more resistant.
Scientists who study sleep have divided it into four stages or phases. An electroencephalogram (EEG) records your brain waves when you sleep and shows the different stages, from wakefulness to deep sleep.
Stage 1 sleep is the lightest and is characterized by low voltage and out-of-sync and sometimes constant activity. After a few seconds or minutes, phase 2 begins and the EEG shows a graph with characteristically shaped waves, called sleep spindles and some high-voltage peaks, called K complexes. Phase 3 then begins , with the appearance of delta waves (high voltage activity), and the cycle ends with phase 4 in which, sometimes, delta waves occupy the majority, the last two phases are known as "slow wave sleep" or "deep sleep ”.
There are various sleep disturbances or disorders such as insomnia or difficulty sleeping, sleepwalking, teeth grinding, nightmares, narcolepsy (where the person experiences paralysis during sleep), and sleep apnea (interruption of breathing).
On the other hand, a dream is that which represents a desire or fantasy to be achieved, with effort or magically. In other words, something that is desired and pursued, but that is very difficult to achieve.
