There are numerous causes of nighttime cough. Many of these may cause a cough during the day, but the most common causes of nocturnal cough are illnesses like colds, viruses, allergies, asthma, and bacterial infections of the respiratory tract and sinuses. A few illnesses or conditions from these groups are associated with worsening cough at night. Other factors that may result in a cough at night include specific medications or illnesses like gastrointestinal reflux disease (GERD) and congestive heart failure (CHF).
Any type of severe sinus or airway congestion might create some worsening of cough at night. Lying down makes it difficult for phlegm to drain, and mucus can accumulate in the throat, stimulating a nighttime cough. Other factors like dry air or exposure to home allergens can create more coughing as well. Slightly elevating the head with an extra pillow for adults or a pillow under the mattress for children may help with gravity-based coughing problems, and using humidifiers and trying to reduce allergens in a home could improve humidity or allergy-based coughing.
A few infections are especially noted for their worsening cough, and both most commonly occur in children. Croup, which can occur with many viruses or bacterial infections, causes a barking, seal-like cough that may begin a few hours after a child goes to bed. Whooping cough or pertussis also tends to be worse at night. These conditions improve with time, and croup can respond favorably to a more humid environment.
Allergic conditions may often cause a nighttime cough that doesn’t occur much in the day. This is explained by the fact that many people are allergic to things in their home, and after being out all day, they come home to exposure to allergens that cause sinus problems. By the time they are ready for bed, the sinuses and respiratory tract may be very irritated, creating nocturnal coughing. On the other hand, when people leave home for the day, symptoms improve. Asthma, which may or may not be caused by allergy, is another condition that could be characterized by a nighttime cough.
Sometimes nocturnal coughing is unrelated to viruses, bacterial infections, allergies or asthma. GERD is an additional offender that causes stomach acid to flow back up the esophagus. This irritation can create a constantly runny nose, and in some people it causes a cough that worsens at night, due partly to gravity. Congestive heart failure, where the heart’s function is decreased, has a cough that worsens when lying down as a primary symptom. When there is no clear cause of cough, people should get medical help to rule out conditions like asthma, GERD, and CHF.
Another cause of nighttime cough is certain medications used to treat heart failure and high blood pressure. In particular, ACE inhibitors like captopril, lisinopril, and enalapril often provoke cough that may be most active at night. If this interferes with sleep, there are other antihypertensives that might be tried.