Lying flat can not sleep for many reasons, mainly and mental factors, sleep habits and disease factors, etc. 1, mental factors: patients recently or long-term excitement, anxiety, high tension, stress, neurasthenia, etc., the cerebral cortex will be excited, it is not easy to sleep, then not only lying flat can not sleep, may not be easy to sleep lying on the side; 2, sleep habits: some people’s sleep time, sleep position, sleep environment, etc. Have become a habit, part of the population is accustomed to sleep on the side, if replaced by lying flat position may not sleep; 3, disease factors: patients with heart and lung disease, such as bronchitis, emphysema, heart failure, etc., lying flat may be easy to breathe, can not sleep. Part of the population lying flat when sleeping tongue back, snoring more serious, will appear sleep apnea syndrome, may be suffocated awake, side lying is conducive to avoid this phenomenon. If the occasional symptoms of lying flat sleep, generally not serious, through the daily adjustment will gradually ease after, the body may not affect much. However, in the case of serious insomnia, it is still necessary to go to the hospital for examination and treatment.