A written and informed consent was obtained from the participants prior to the study. After taking the baseline data of name, age and gender, height and weight of the participants along with basal blood pressure werebe recorded. Then, the participants were asked to answer two questionnaires i.e., Sleep Quality Scale (SQS) and Pittsburgh Sleep Quality Index (PSQI), based on their subjective sleep experience. After completing the sleep questionnaires, a battery of neurocognitive tests were performed by the participants namely, letter cancellation test, forward and backward digit span recollection test, Montreal cognitive assessment test (all the questionnaires are attached).

            After the baseline recordings, all the participants were divided broadly into 2 categories with their present preferences of sleeping in dark or light. From this broad category participants were randomly divided into 2 groups each (Fig-1) with one group choosing to have change in sleeping setting to light or dark and one group did not change in any sleep settings. According to their division of group, the participants were asked to change their settings of the sleeping room in terms of light/darkness for a period of one month. After a month of exposure to darkness or light, all the parameters recorded at the baseline were recorded once again and the questionnaire answered at the baseline were answered by the participants again and the data before and after the change in sleep in darkness or light was compared by using Student’s paired t test. Also the data in between the groups after the change of room darkness or light was analyzed by using One Way ANOVA