ORIGINAL ARTICLE Sleep Pattern of Adolescents in a School in Delhi, India: Impact on their Mood and Academic Performance Ruchi Singh 1 & Jagdish C. Suri 2 & Renuka Sharma 1 & Tejas Suri 3 & Tulsi Adhikari 4 Received: 21 September 2017 /Accepted: 15 February 2018 /Published online: 16 March 2018 # Dr. K C Chaudhuri Foundation 2018 Abstract Objectives To examine the sleep pattern and observe differences in sleep routines, phase preferences, mood, attendance, and academic performance among different adolescent age students. Secondly, to observe the age at which sleep phase transition and changes in sleep requirement become evident. Methods A cross-sectional study was conducted among 501 students (aged 11–15 y) of a school in Delhi, India. Students were evaluated for their sleep patterns, sleep duration, habits of napping, quality of sleep, sleepiness, depression, phase preferences by self-reported school sleep habits survey questionnaire along with school performance and attendance. Results Significant differences were found in sleep pattern of students aged 11–12 y and 13–15 y. Bedtime shifted to a later time with increasing age but early morning schools kept the wake time same, leading to a decline in total sleep duration of older adolescents. Older adolescents had higher depression but poor attendance and academic performance. Prevalence of sleep deprivation increased with age, from 83.7% to 87.1% in 11–12 y to 90.5% to 92.5% in 13–15 y. Conclusions The study clearly identifies 12–13 y as age of transition of sleep pattern among adolescents. Though significant differences were found in the academic performance, mood and attendance among preteens and teens but no direct association was seen between academic performances and sleep pattern. A complex multifactorial association between sleep patterns, attendance, mood and academic performance which may change over days, months, or years should be explored further in a longitudinal follow up study. Keywords Sleep deprivation . Depression . Sleep . Students . Adolescents . Mood . School performance Introduction Sleep is a biological necessity for regeneration of mind and body. Unfortunately, it is an easily compromised part in daily routine. Students between ages, 10 to 19 y who are in stage of transition from childhood to adulthood, are especially vulnerable to sleep loss [1]. Researchers have shown that there is a sleep phase shift during adolescence [2]. Total sleep re- quirement remains between 8.25 to 9.2 h/night for optimal daytime alertness but sleep onset time is delayed [3, 4]. Inconsistency between sleep pattern, i.e., sleeping and waking routines on weekdays and weekends increases as one grows to an adolescent [5–8]. Adequate sleep is essential for normal daytime functioning, learning, cognition, physical and psychological well-being [9]. In spite of increased sleep requirements, adolescents experience sleep debt and suffer unknowingly from its consequences i.e., daytime sleepi- ness, mood changes and poor school attendance [4, 10, 11]. Poor sleep badly impacts attention, memory and ac- ademic performance [12–14]. Various cultural, social, environmental, and family factors are responsible for changes in sleep patterns [15]. Hence this study was undertaken to examine these changes in sleep pat- tern and observe differences in sleep routines, phase prefer- ences, mood change, attendance, and academic performance * Jagdish C. Suri docjcsuri@gmail.com 1 Department of Physiology, VMMC and Safdarjung Hospital, Delhi, India 2 Department of Pulmonary, Critical Care and Sleep Medicine, Safdarjung Hospital, New Delhi 110029, India 3 Department of Medicine, All India Institute of Medical Science, New Delhi, India 4 National Institute of Medical Statistics (ICMR), Ansari Nagar, New Delhi, India The Indian Journal of Pediatrics (October 2018) 85(10):841–848 https://doi.org/10.1007/s12098-018-2647-7