Allergic rhinitis is a prevalent disease in developed nations, and its prevalence has been increasing throughout the world. Nasal congestion is the most common and bothersome symptoms of rhinitis. Congestion is associated with sleep-disordered breathing and is thought to be a key cause of sleep impairment in individuals with rhinitis. The end result is a decrease in quality of life and productivity and an increase in daytime sleepiness. Treatment with intranasal corticosteroids has been shown to reduce nasal congestion. Data on sleep-related end points from clinical trials of intranasal corticosteroids indicate that this reduction is associated with improved sleep, reduced daytime fatigue, and improved quality of life. Other therapies, such as montelukast, also have a positive influence on congestion and sleep. This review examines nasal congestion and the associated sleep impairment of allergic rhinitis patients. It explores the adverse effects of disturbed sleep on quality of life and how these conditions can be reduced by therapies that decrease congestion.