Risk assessment of road traffic accidents related to sleepiness during driving: a systematic review

Background: Injuries due to accidental crash are the 8th leading cause of death worldwide. Sleepiness results in disrupted neurological function and is a major risk factor for road traffic accidents. Aims: This systematic review assessed the relationship between sleepiness during driving and road traffic accidents. Methods: A systematic review was conducted using online databases such as Wiley Online Library, JSTOR, Medline, and PubMed. Full-text, English language articles published between May 2000 and November 2020 were retrieved. Road traffic accident was set as the outcome of interest and sleepiness during driving as the exposure. The review included studies containing adjusted risk estimates (95% confidence interval). Ten cross-sectional studies (N = 55,945), 5 casecontrol studies (N = 3821), and 2 cohort studies (N =16,875) were included. Results: Over 50% of the participants in the different studies experienced sleep deprivation ranging from 3.5% to 67.3%. Abe et al. reported the highest (58%) frequency of sleepiness during driving in their cross-sectional study in Japan, and Nabi et al. reported the lowest (1.1%) in their cohort study in France. Conclusion: Sleepiness and sleep deprivation were related to road traffic accidents; and sleep deprivation was the main contributor to drowsiness while driving.