Actigraphy has become increasingly recognized as a useful method to study sleep/wake patterns and activity monitoring. It is a reliable tool for confirming a diagnosis and evaluating the effect of treatments for sleep problems in patients with primary psychiatric diagnoses such as schizophrenia. In addition, actigraphy is an objective measure that circumvents the lack of insight and often unreliable self-reporting of mental health related problems. However, the literature regarding the use of actigraphy in research and clinical applications related to severe psychiatric populations is scarce. Amalgamation of the evidence is needed to advance the use of actigraphy in psychiatry. We summarized the literature to date related to the use of actigraphy in patients with psychotic disorders, specifically schizophrenia. We conducted a systematic review of journal databases. Sixty-six studies emerged from the search of the electronic search engines, 14 were RCTs/case-control studies and 14 were review/guideline papers and others were case studies. Results of the RCT/case-control studies comparing the use of actigraphy with patients versus control were summarized. Actigraphy not only allows for the objective evaluation of sleep habits and circadian rhythm disorders, but also helps to clarify and compare sleep and activity patterns among severe psychiatric disorders such as schizophrenia. Additionally, actigraphy data can be used as an outcome measure for changes in sleep patterns either when primary psychotic disorders are treated and/or when the sleep disturbance associated with the psychotic disorder is treated. Finally, actigraphy serves as a supplementary tool to study neuropathology of movement-related psychiatric disorders including schizophrenia.