Perennial allergic rhinitis (PAR) often causes sleep disturbances and associated daytime somnolence, thus resulting in a poor quality of life. Various clinical interventions in patients suffering from the disorder seek to improve symptoms and quality of life. Additional studies are needed to establish whether the alleviation of PAR symptoms, particularly the reduction of congestion, will improve sleep quality and reduce daytime somnolence. This study seeks to determine whether treatment with montelukast is more effective than placebo in reducing nasal congestion and sleep disturbances, resulting in reduced daytime somnolence and fatigue in patients with PAR. Thirty-one subjects were enrolled in a double-blinded, placebo-controlled study using Balaam's design. Patients were treated with montelukast or placebo. Collected subjective data included a daily diary recording nasal symptoms, sleep issues, and daytime fatigue, the Functional Outcomes of Sleep Questionnaire, the Epworth Sleepiness Scale, Juniper's Rhinoconjunctivitis Quality of Life Questionnaire, the Rhinitis Severity Scale, the Calgary Sleep Apnea Quality of Life Index, and Trail Making tests. Subjects treated with montelukast, compared with placebo, showed a statistically significant improvement in daytime somnolence (p = 0.0089) and daytime fatigue (p = 0.0087), with both factors improving with montelukast and worsening with placebo. In a small cohort of subjects, montelukast, when compared with placebo, improved the symptoms of PAR and reduced the fatigue and daytime somnolence associated with the disorder.