An Overview of Disease and Health Research Vol. 6

Chronotypes represent an individual’s natural preference for sleep and activity timing within the 24-hour day, governed by circadian rhythms and the suprachiasmatic nucleus (SCN). This review explores how chronotypes categorised as morning, evening, and intermediate affect various dimensions of health and behaviours. It examines the biological underpinnings of chronotype, including hormonal and genetic mechanisms, and the tools used for its assessment, such as the Morningness-Eveningness Questionnaire, Munich Chronotype Questionnaire, actigraphy, and sleep diaries. The study highlights significant associations between chronotype and physical health outcomes, including sleep quality, metabolic disorders, cardiovascular health, and immune function. In terms of mental health, evening chronotypes are particularly vulnerable to depression, anxiety, and stress-related disorders, often due to misalignment between biological rhythms and societal demands. Furthermore, chronotype influences cognitive functioning, academic performance, and the impact of shift work, particularly among working adults. Understanding and aligning daily routines with an individual’s chronotype can lead to improved well-being, enhanced productivity, and reduced health risks. The findings underscore the importance of recognising chronotype differences to improve health outcomes, optimise daily functioning, and tailor interventions in educational, clinical, and occupational settings. Future research should continue to explore chronotype-based interventions and policies that respect biological diversity in human functioning.