摘要：Background: Exposure to light from viewing devices at night disturbs the circadian rhythm, especially sleep. The study aimed to assess (a) extent to which smart phones are used by medical undergraduate students during bedtime and to find their quality of sleep (b) the association of quality of sleep and cell phone variables. Methods: A cross sectional observational study was conducted among 450 medical undergraduate students. The participants completed Pittsburgh Sleep Quality Index (PSQI) questionnaire and a validated semi structured questionnaire consisting of demographic details and cell phone variables. Results: By dividing the subjects into three groups according to their usage (Group I 1 hour, Group II 1 to 2 hours, Group III 2 hours), Group III respondents had significant prolonged sleep latency, reduced sleep duration, sleep inefficiency and daytime sleep disturbances ( P 0.05). Lack of awareness about night shift mode, lying posture use while using phone during bedtime correlated with poor quality sleep ( P 0.05). Conclusions: Awareness about the negative impact of evening exposure to viewing devices on sleep and health should be emphasized.
