10.22376/ijpbs.2019.10.1.p1-12 Volume 6 Issue 1 2015 (January - March) Shift workers are being targeted to work for greaterThan 10hrs in emergency medical services to cover 24 hours service, who is prone for sleep deprivation. Sleep is regulated by the balance between circadian rhythm and Homeostatic mechanism. Circadian misalignment which is an altered biological clock, lead to chronic physical illness like obesity, Hypertension, Diabetes mellitus, Ischemic Heart disease &mental illness like Depression , insomnia & Obstructive sleep apnoea in night shift workers. So this prospective study was conducted with 100 night duty nurses (males-50 and females-50) by a pretested questionnaire to reveal the sleep hygiene, unhealthy sleep related behaviors & physical & mental distress. Data was analysed with Descriptive statistics using SPSS software 21. Night Shift workers are suffering from Excessive sleepiness, snoring, overweight, obesity H/O occupational error due to difficulty in concentration due to lack of sleep. M.MUHIL, UMAPATHYSEMBIAN AND THIRUMALAIKOLUNDU SUBRAMANIYAN Circadian Rhythm, shift work disorder, sleep hygiene and sleep deprivation 664-669