Rationale. Previous studies have suggested that asthmatics have an increased incidence of sleep disturbances. However, these studies have been limited by reliance on population surveys or small numbers of participants. Objectives. We sought to measure sleep quality and daytime sleepiness in a cohort of symptomatic asthmatics and to measure the effects of improved asthma control on sleep quality. Methods. Data were collected in sub-study of a large multi-center randomized double-masked controlled trial of mild-moderate asthmatics evaluating the effect of low-dose theophylline on asthma control in comparison to montelukast and placebo. Each participant was administered sleep symptom questionnaires at randomization and at the final visit (6 months after randomization). These included the Pittsburgh Sleep Quality Questionnaire (PSQI) and the Epworth Sleepiness Scale (ESS). Measurements and main results. Data were available for 487 participants. Baseline mean values were: age 40 ± 15 years, 74% female, forced expiratory volume in 1 second (FEV₁) 79 +16 percent predicted, Juniper Asthma Control Questionnaire (ACQ) score 2.35 ± 0.63, PSQI 7.8 ±4, and ESS 8.5 ±4.9. There were no significant differences in the PSQI or ESS between the three treatment groups. Significant correlations were found at baseline between the global PSQI score and ACQ and quality of life and marginally with lung function. Significant correlation existed between improvements in PSQI and ESS with improved asthma control and quality of life. Conclusions. Sleep disturbances are common in asthmatics and are associated with asthma control and quality of life. Clinicians caring for asthmatics may need to complete a more detailed sleep history in patients with poorly controlled asthma. In addition, low-dose theophylline does not seem to impair sleep quality in asthmatics.