In the European Union, over 20 million people suffer from asthma. During the 1990s there was a rapid decrease in asthma mortality, probably related to the increased use of inhaled corticosteroids (ICS). However, during the last decade, asthma mortality rates have plateaued, and a consistently high proportion of patients have uncontrolled asthma. As a result, many patients with asthma still have impaired quality of life and suffer from chronic respiratory symptoms, often including night-time symptoms, causing sleep disturbance, excessive daytime sleepiness and decreased work productivity.