During the "sleep" phase there is a transient loss of consciousness and a partial reduction of various biological functions; in this phase, for example, the production of corticoid and adrenergic hormones is reduced, vice versa the secretion of growth factors increases. The quality of sleep also determines the quality of daytime life.
Several clinical studies have been carried out to analyze sleep from a physiological point of view, thanks also to the "aid of electroencephalography, electrooculography and electromyography. From these studies it emerged that sleep is not constant, but made up of cycles, each of which consists of of an NREM phase - or "orthodox sleep" - and a REM phase - or "paradoxical sleep", since pupil movements have been observed. In this last phase, which generally occurs 4/5 times during the night, we have dreams.
More specifically, the stages of sleep are:
- Stage 1: NREM, represents falling asleep in which brain activity slows down;
- Stage 2: NREM, light sleep phase in which brain waves are similar to those seen in the waking phase;
- Stage 3: NREM, a phase of deep sleep characterized by very slow and large brain waves;
- Stage 4: NREM, phase of deep sleep in which the body regenerates itself, restoring metabolic reserves;
- Stage 5: REM, in this stage the brain waves show eye movement.
The duration of each stage varies from individual to individual, based on diversified factors, including environmental ones.
From this analysis we will say that sleep is not a passive event, but the time / moment taken by the human organism to catalog all the useful events of the day and delete what is deemed useless. In these phases, however, the state of vigilance is always maintained , which allows the individual to react to sensory stimuli of danger; the correct processing of past daytime events allows the subject to face the new day without anxiety and depression.
it is a pathology that does not allow the patient to sleep for a number of hours sufficient to guarantee circadian balances; generally insomnia is characterized by difficulties in falling asleep, repeated nocturnal awakenings and very short periods of sleep.
Insomnia can be divided into:
- Occasional: that is, it can happen from time to time, in which case a pharmacological intervention is not necessary;
- Transient: when it persists for at least a few weeks, usually due to collateral pathologies or strong emotional states;
- Chronic: when it lasts for more than a month; in this case it is a real pathology to be treated with suitable drugs.
The causes of insomnia can be different: physical or mental disorders, the use of drugs that have insomnia as a side effect, the use of drugs and abuse.
There is also a fourth type of insomnia, called "inorganic" or primary, the causes of which are not known.
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