Sleep aids are drugs which are aimed at maintaining a sufficiently long and deep sleep. The group of sleeping pills is extensive and includes medicines that are heterogeneous in composition and mechanism of action. Small doses of these medicines have a relaxing and calming effect.
There are three generations of drugs used to eliminate the symptoms of insomnia:
•    Barbiturates, antihistamines, chloral hydrate.
•    Hypnotic benzodiazepine series.
•    Non-benzodiazepine hypnotics: cyclopyrrolones (zopiclone), imidazopyridines (zolpidem), pyrazolopyrimidines (zaleplon).
Principles for the appointment of sleeping pills
The powerful soothing effect of powerful hypnotics allows you to restore the desired duration of a night's rest quickly. However, there is a downside: 
•    the change in the ratio and period of sleep phases; 
•    violation of daily activity; 
•    the formation of addiction; 
•    withdrawal syndrome 
Taking a sleeping pill for a long time is prescribed only in a situation if the cause of the sleep disorder is not known.
Sedatives are used as agents that have a powerful effect on the human body in cases where another cure for insomnia is powerless.