Why Do I Feel Out of Breath When Lying Down?

Feeling out of breath when lying down, called orthopnea, typically indicates heart failure or fluid accumulation in the lungs. This occurs because lying flat allows fluid that has pooled in your legs during the day to redistribute to your chest cavity, making breathing more difficult. Heart failure affects over 6 million Americans and causes the heart to pump less effectively, leading to fluid backup. Other causes include sleep apnea, anxiety disorders, or lung conditions like asthma. Most people with orthopnea need to sleep propped up on 2-3 pillows to breathe comfortably. If you consistently experience shortness of breath when lying down, especially if accompanied by swollen ankles or chest pain, seek medical evaluation promptly as this can indicate serious cardiovascular issues requiring treatment.