Difficulty in breathing for a while may be caused by emotional excitement, asthma, cardiac insufficiency and other factors. 1. Emotional excitement: when a person is emotionally excited, he or she may involuntarily breathe heavily and experience dyspnea, and as the emotion calms down, the dyspnea symptoms may disappear. So, breathlessness may be caused by emotional excitement. 2. Asthma: During an asthma attack, there may be a restriction of airflow, which may be manifested as breathlessness. Asthma is mostly caused by inhalation of allergens, and if the allergens are removed, the symptoms may disappear, and the situation of breathlessness will be better in a while. 3. Cardiac insufficiency: The blood in the lungs has to flow back into the left heart. If cardiac insufficiency occurs, it may lead to stagnation of blood in the lungs under certain circumstances, such as strenuous exercise, lying down to sleep, etc., which will lead to shortness of breath. However, when the factors that cause shortness of breath are eliminated, such as resting or sitting up, it will lead to shortness of breath that will disappear after a while. If you are short of breath, you should consult a doctor for a complete examination under the doctor’s guidance to determine the cause of the problem and take active treatment.