Summer Research Fellowship Programme of India's Science Academies


Sreeraksha P.S

Department of Water and Health, JSS Academy of Higher Education and Research, Mysuru

Prof. Sheeba Vasu

Behavioural Neurogenetics and Chronobiology Laboratory, Jawaharlal Nehru Centre for Advanced Scientific Research, Bengaluru


Our life is structured by the constant interaction of solar, social and biological cycles, regulated by three different clocks. The solar clock is responsible for maintaining the light and dark phases of the diurnal rhythm in accordance with the rotation of the Earth while playing a non-trivial role in modulating temperature in a cyclic fashion throughout the day. This represents the solar day comprising of 24 hours. The social clock is governed by our societal obligations and dictates our daily schedules during workdays and free-days. Thus, indirectly affecting our sleep timings. The endogenous, innate biological clock also known as the circadian clock regulates the sleep-wake cycle of the body. The importance of this clock is explicit during jet lag, shift work, or adjustment to Daylight Saving Time. Humans show large differences in preferences of sleep and wake times. These individual differences give rise to a continuum of chronotypes that range from early to late types, commonly known as “larks” and “owls”. Larks can wake up without the aid of an alarm at an earlier hour and find it difficult to stay up late in the evening. Owls on the other hand, prefer to work late into the night and sleep much later than most of the population. Chronotype is largely regulated by the circadian clock and is influenced by both changes in the clock genes and environmental factors like exposure to sunlight, shift work, consumption of stimulants etc. Due to societal obligations that might interfere with sleep preferences, people tend to shift their sleep and activity times by several hours between workdays and free days. This gives rise to sleep debt which is later compensated for on the weekends causing lengthening of sleep duration by several hours. This discrepancy of sleep schedule between workdays and free days, between social and biological time, is termed as Social Jetlag. Social jetlag has adverse effects on learning, memory, vigilance, performance and is detrimental to the overall quality of life. The ChronoType Questionnare (CTQ) for adolescents and young adults of India is designed on the chassis of Munich ChronoType Questionnaire (MCTQ) and might be better suited to the Indian population. This can be used for profiling sleep behaviour and sleep patterns across Indian adolescents and young adults. It can also be employed in the study of social jetlag in these individuals.

 Keywords: Biological clock, circadian, chronotype, social jetlag, human

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