Introduction: Cortisol secretion is regulated by circadian rhythm, which is influenced by zeitgebers like light. In India, the entire country operates under a single time zone, Indian Standard Time, which may not align with the local sunrise timing across different regions.
Aims: This study aimed to compare the basal serum cortisol levels between 06:00 AM and 09:00 AM in Guwahati, Assam, where sunrise occurs earlier compared with the western part of the country.