Background: Accuracy, speed, efficiency, and applicability of activities in the workplace are amongthe most important effective factors on people's productivity, which is in turn affected byenvironmental factors, such as light. Therefore, the present research aimed to review the studiesperformed about the effects of light on attention and reaction time.Sudy Design: A systematic review.Methods: This review study systematically searched articles from ۲۰۰۰-۲۰۱۹ in databases ofGoogle Scholar, ISC, SID, Magiran, Web of Science, Science Direct, PubMed, and Scopus usingkeywords of light, lighting, attention, and reaction time. The titles and abstracts of articles containingrelevant results over the past ۲۰ years were extracted. Thereafter, they were categorized andanalyzed according to the title, author name, publication year, study method, study type, andevaluation results.Results: Based on the results, the light with shorter wavelengths, higher intensity, and higher colortemperature led to suppressed melatonin, higher consciousness, less somnolence, increasedattention, and faster reaction time. Simultaneous exposure to harmful levels of environmentalfactors affects cognitive and physiological parameters, acting independently with a separatemechanism or synergistically with a similar mechanism. The best light in the regulation ofpsychological, biological, and cognitive processes is bright daylight in the morning with a shortwavelength, high intensity, and more lasting effects.Conclusion: As evidenced by the obtained results, light is a powerful modulator of non-visualperformance in cognitive tasks. The wavelength, color temperature, and light intensity modulatebrain responses to cognitive tasks, including attention and reaction time. Therefore, theseparameters, along with personal and environmental factors, should be considered in designing andusing light.