The cough in cough variant asthma is a dry cough that lasts for more than 6 to 8 weeks. It can occur any time of the day, though coughing at night that wakes you up is common with CVA. Try using a humidifier to lessen the coughing at night and moisten the air as the cough in CVA is dry.The cough also often worsens during exercise. Aside of course from taking meds to relieve cough.