Why do people suffer from insomnia and what bad effects insomnia can bring?

There are many reasons for insomnia, the most common is long-term mental stress, if this will lead to neurasthenia in patients for a long time, patients will first appear attention loss, memory loss, drowsiness, fatigue and other conditions, then the patient's immunity will also be affected, will often get sick, gastrointestinal function will also deteriorate.