Those whose asthma is keeping them up at night might find that part of the problem lies in their nose.
A new study has linked inadequate treatment of allergic rhinitis - more commonly known as having a "sensitive nose" - with a 50 per cent increase in asthma symptoms at night.
"If you treat your asthma, you should be treating your sensitive nose at the same time," said Dr Tan Ngiap Chuan, the study's principal investigator, and a family physician and director of research at SingHealth Polyclinics.
For these people, excess mucus accumulates during sleep and irritates the throat, which could trigger the coughing.
The study also found that when patients follow proper instructions on how to cope with their symptoms, the risk of such night-time problems occurring drops by as much as 63 per cent.
The study, by SingHealth Polyclinics and Duke-NUS Graduate Medical School, hopes to encourage both doctors and asthma patients to keep a closer eye on their medical condition.
Two of Dr Tan's patients, sisters Lim Kim Liang, 77, and Lim Kim Joo, 84, suffered from asthma as children and have been seeing him for around 10 years.
The elder Madam Lim said their asthma improved after Dr Tan explained to them how to take their medication properly. "My asthma used to be a lot worse," she said. "I couldn't sleep well and would cough all the time at night."
Asthma affects about one in 10 Singaporean adults, with a third experiencing night-time symptoms ranging from breathlessness to constant coughing that wake patients up and leave them tired during the day.