It’s annoying when you awaken at night with a hacking cough. Sometimes a nighttime cough is due to a respiratory infection, but, in some cases, the raspy cough only occurs when you lie down to sleep. What causes a nocturnal cough – and why does it only happen at night?
Common Causes of Night Cough: Could It Be Asthma or Allergies?
Asthma and post-nasal drainage are two common, but underappreciated, causes of nocturnal cough. Allergies cause the mucous-producing cells lining the nasal passages to become inflamed and produce more sticky mucous than usual. When you lie down to sleep at night, gravity pulls these secretions into the back of your throat – which causes a persistent nighttime cough. This can usually be corrected with nasal steroids, decongestants, or antihistamines – once you know what’s causing it.
Asthma is another frequent cause of night cough – a condition that’s called nocturnal asthma. No one knows exactly why asthma causes nighttime coughing, but lying flat in bed seems to increase airway resistance – leading to bronchospasms. This may be worse if you sleep in a dry environment. Surprisingly, nocturnal cough may be the only sign of asthma. If you’re hacking consistently at night for no obvious reason, your doctor may want to see if your symptoms respond to treatment with an asthma inhaler.
Nocturnal Cough Can Be a Sign of GERD
GERD is another name for gastro-esophageal reflux disease, a condition where acid travels backwards from the stomach into the esophagus due to a weak esophageal flap. Some people who have this condition have frequent “heartburn” and a sour taste in their mouth, but others only have a nighttime cough. Lying flat in bed, especially after a large meal, makes it easier for acid to backflow into the esophagus and throat – which can lead to the characteristic nighttime cough.
A More Serious Cause of Coughing at Night
Coughing at night can also be a sign of congestive heart failure. This is condition where the heart doesn’t pump as effectively as it should. This causes fluid to build up in the extremities or in the lungs. When a person with congestive heart failure lies flat, they become short of breath and may develop a persistent cough. Anyone who has a cough with shortness of breath or fluid retention needs evaluation by a doctor to rule out this condition.
Other Causes of Nocturnal Cough
Coughing at night can be a sign of viral or bacterial infection or more serious lung conditions – and even lung cancer. Certain medications can also cause a cough – especially ACE inhibitors used to treat high blood pressure. The bottom line? If you have a nighttime cough, don’t ignore it. It could be a sign of something as simple as post-nasal drainage – or something more concerning.
Merck Manual. Eighteenth edition. 2006.