Abstract
            Introduction: Drowsiness and fatigue during driving is one of the major causes of traffic accidents,  morbidity, and mortality in societies. Known electroencephalography (EEG) as a gold standard in  fatigue detection, this study aims to determine the alterations in different brain regions in fatigued  and drowsy drivers.  
  Methods: The databases PubMed, Scopus, Web of Science, and Embase have been systematically  searched for published studies until September 1, 2023. Also, the references of the relevant  articles have been searched manually. Reporting the quality assessment of the studies has been  done by the Joanna Briggs Institute (JBI) critical appraisal tool for experimental studies. The study  purpose was achieved using appropriate statistical methods.  
  Results: Sixty-five eligible studies consisting of 1450 participants were included. The most  common age and gender between participants is young males. The majority of the studies were  held in high-income countries. Simulated car driving studies are utilized frequently in the studies.  Common brain-wave changes seen in various regions include increased alpha in the occipital  area (51.7%) and decreased alpha in the frontal region (eight out of eight simulated driving  studies), decreased beta in the frontal region (25.8% of driving simulated studies), increased  theta in the frontal region (36.2%), and decreased gamma in the central and temporal areas.  Delta waves increase throughout the brain in an equal proportion.  
  Conclusion: The occipital alpha increase, frontal beta decrease, frontal theta increase, and  central and temporal gamma decrease, are frequent findings among the studies reporting fatigue  and drowsiness. Based on the discrepancies and inconsistencies reported in EEG results, the  detection of fatigue and drowsiness in the driving task via EEG data should be done with caution.