Y the pts with COPD hav dysnoea in early morning?

Position/therapy/ Supine position in COPD aggravates airway diameter as a consequence of gravity. Thus a narrowed airway is more narrow when supine. It is why COPD pts often sleep in a chair.Also most pts are at the nadir of therapeutic therapy effects in early morning ie they have little active medicine on board. Also circulating steroids are lower in early am thus providing less anti-inflammatory mechanisms.
Airflow is lowest at. There is normal diurnal variation in airflow in all human beings, the peak airflow is lowest at around 4 am .This happens in people without any COPD as well. As the flow is limited in patient's with copd, there are symptomatic when the flow rate falls below a critical level. To avoid this problem, patient's with COPD should. Use a long acting bronchodilator at bed time.