Our daily physical activities are controlled by the autonomic nervous system. Regarding sleep, the sympathetic nervous system, which is active during the day, switches to the autonomic nervous system at night to promote relaxation and rest, calming irritability and tension, and improving insomnia.
However, when the autonomic nervous system becomes unbalanced due to stress or other factors, the parasympathetic nervous system does not function properly even at night, and the sympathetic nervous system remains dominant, leading to unpleasant symptoms such as insomnia, persistent fatigue, and loss of appetite.