Which symptom of heart failure is typically worsened during the night and may wake a patient from sleep?

• A. Weight gain
• B. Paroxysmal nocturnal dyspnea
• C. Edema
• D. Chest pain

Answer: (B)

Paroxysmal nocturnal dyspnea reflects how fluid redistribution during sleep worsens left-sided heart failure. When a person lies flat, more blood returns to the heart (increased venous return), raising pulmonary pressures and causing fluid to shift into the lung tissue. This sudden pulmonary congestion triggers abrupt shortness of breath that often wakes the person from sleep, sometimes with coughing or wheezing.

This night-time symptom is distinct from peripheral edema or weight gain, which are more chronic signs of fluid retention, and from chest pain, which isn’t typical of heart failure. Orthopnea (dyspnea when lying flat) is related but refers to symptoms occurring specifically with lying down; the hallmark here is the sudden awakening due to acute dyspnea at night.