Orthopnea involves difficulty breathing while lying down. If you notice that you breathe easier when propped up with a pillow, you may be experiencing orthopnea, which is often a sign of more serious health complications. Stress can also exacerbate orthopnea, as well as other health problems [source: Mayo Clinic]. Orthopnea should not be taken lightly; don't simply attribute your difficulty with breathing to being stressed. Seek medical attention to determine if you have a more serious health condition that requires treatment.

Orthopnea is a common symptom of pericardial effusion and heart failure. Pericardial effusion involves fluid buildup in the heart and is a serious condition. The pericardium is sac-like and holds the heart. A healthy pericardium has a little bit of fluid. A buildup of fluid, however, causes increased pressure on the heart, leading to distressing symptoms, such as orthopnea. Pericardial infusion, if left untreated, can lead to serious health problems and even death. Typically, pericardial effusion is the result of heart surgery, injury or disease. In addition to orthopnea, you may also experience chest pain, coughing, dizziness, rapid heart rate and anxiety. Treatment typically includes anti-inflammatory medication or more invasive procedures, such as pericardiocentesis and open-heart surgery [source: Mayo Clinic].

Another cause of orthopnea is congestion in the lungs. Fluid buildup or congestion in the lungs can result in difficulty breathing while lying down. This is called pulmonary edema. When you're in a lying-down position, the fluid and blood from your feet and legs goes up to the lungs; this ultimately leads to problems breathing and problems with your heart. Orthopnea can also result in swelling of the feet and ankles. Treatment typically includes a low-sodium diet, diuretic medication, and other prescription medication. You may even require hospitalization.