Ragini, You probably have a question which is medically referred to as Cardiac Asthma. In simple terms it means a Heart condition causing Asthma like symptoms, of cough especially on lying down or at night.When one is significantly Anaemic there is an associated low protein level in the Blood ( as reflected by total Protein & especially Serum Albumin ). This results in an inability of the blood to keep the fluid within the blood vessels & this then seeps out of the blood vessels into the tissues of the lungs, causing the lungs to become less elastic & less efficient in transferring Oxygen.Hence the shortness of breath. At night fluid gets absorbed from the lower limbs & peripheries because of the elimination of gravity on lying down.The abdominal contents, more so after a heavy dinner, pushes the Diaphragm upwards , into the Chest , on lying down. Combined by a suppression of the Cough Reflex in Sleep, resulting in greater build of fluid or Phlegm in the night,before the cough kicks in, often very disturbingly. Firstly it means that your lung congestion requires treatment, to cure the fluid accumulation, and hence the cough. Secondly , the cause of your Anaemia , needs to be investigated and treated. This may require Blood transfusion , to make you feel better, before your body can rebuild your Haemoglobin levels to more normal levels.