Introduction: Nocturnal worsening of asthma symptoms is a common feature of asthma. Patients with nocturnal asthma have nighttime increases in airway inflammation and decreases in steroid responsiveness. Physical exercise training improves general asthma control. However considering the physiological differences between asthma patients with daytime and nighttime symptoms, effects of physical exercise between these two types of asthma could be different. The aim of this systematic review is to explore the effects of physical exercise on sleep quality, and nocturnal asthma symptoms prevalence and severity in adults with asthma.Methods: Searches were conducted in MEDLINE, Embase, Cochrane Central Register of Controlled Trials, CINAHL and SPORTdiscus. Search strategies included a combination of text words and subject headings relating to: (1) physical activity or exercise, (2) asthma, and (3) trials. Questionnaires or diaries were used to ask participants whether they had any nocturnal awakening due to nocturnal asthma symptoms such as coughing or shortness of breath. Authors from studies that did not report nocturnal symptoms but used questionnaires and/or diaries were contacted for detailed information. Studies that provided results on the nocturnal symptoms before and after physical activity intervention were included. Prevalence of nocturnal symptoms was calculated for each study from the percentage of study participants with nocturnal symptoms before and after intervention. Results: The search resulted in 8744 titles from the initial search. We contacted 21 authors and a total of 6 studies were included (Table 1). Included studies assessed nocturnal symptoms using Asthma Control Questionnaire (ACQ) and Asthma Quality of Life Questionnaire (AQLQ). According to the available data, the prevalence of asthmatic adults with nocturnal symptoms was between 50-73% which reduced to 26-56% after physical exercise intervention. In non-obese adults with asthma, supervised physical exercise for at least 12 weeks (3x/wk, 1hr) reduced the nocturnal asthma symptoms prevalence, improved sleep quality, and reduced number of nights with nocturnal awakening. The same duration of non-supervised exercise did not improve nocturnal asthma prevalence. In obese adults with asthma, physical exercise for at least 10 weeks (3x/wk, 1hr) reduced the prevalence of nocturnal asthma and improved sleep quality. Discussion: Our systematic review demonstrated that aerobic physical exercise may improve nocturnal asthma in adults by reducing the prevalence and frequency of nocturnal awakening due to asthma symptoms. Physical exercise training could be used with conventional treatments to improve quality of life and asthma control in patients with nocturnal worsening of asthma.