What factors prevent and help a person to fall asleep?

Interfere with: external stimuli (bright light, loud sound); internal stimuli (pain, hunger, restless thoughts); humoral signals (adrenaline). Help: maintaining a constant rhythm of sleep and wakefulness, conditioned reflexes to the usual rituals of going to sleep; external influences (heat, relaxing factors); internal influences (fatigue); hormonal effects (serotonin).

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.