My girl (now almost 4 yrs old) in last year Oct, same as you all, cough at night all the time and can't sleep. Visit many doctors and take many drugs but couldn't help. Until visit any other doctor, he said she is 氣管敏感 and give her the Singulair to take every night. She is still taking it now and she takes almost a year la. It's kind of under control after taking this drugs for a month, but come back after stopped. Then another doctor tell us that she got Ashma and give us some inhaler (氣管舒張藥) and give it to her when she cough seriously and when 氣管收窄.
IN last couple of days, because of the changing weather, my girl not only take the Singulair, she has to take the inhaler before sleep also.