Sleep is a requisite of a healthy life. Waking up during Brahmamuhruta is mentioned in Sutrasthana 2/1 of Ashatanga Hridaya. Almost all Indian religious texts recommend the same. It means proper sleep and early to bed is indispensable to each other.
A cohort study published in European Heart Journal- Digital Health refers to association of heart diseases with sleep onset timing. To find this, scientists used wrist-worn accelerometer for sleep onset and waking up time of 88026 participants aged 37-73 (years) over a period of 7 days. They enrolled participants during 2013-2015. Researchers included myocardial infarction, heart failure, strike, chronic ischaemic heart disease and transient ischaemic attack excluding fatal cardiovascular diseases. They noted dimorphic patterns based on gender. Females have shown stronger association than males. They suggested more researches to understand the mechanism of such findings. Still some previous study from related aspects have connections, explorations are required.
As many studies have revealed the relationship of biological processes including hormone secretion, sleep-wake cycle, body temperature etc. with circadian cycle. Even works have highlighted the circadian misalignment over long periods of time in relation to elevated blood pressure and other cardiovascular risks. The circadian cycle is under control of suprachiasmatic nucleus of hypothalamus. Some of neurotransmitters in hypothalamus communicate to heart functions and alterations in levels of these neurotransmitters are responsible different cardiovascular problems. Other than this, researches have shown the presence of clock genes in every organ or tissue (except thymus and testis) of mammals to generate gene expression in terms of circadian pathway. Clock genes are allied with environment. Alteration of life-style from natural path, may bring anomalies or polymorphism in clock genes. Studies have revealed the links between anomalies or polymorphism in clock genes with cardiovascular risk, overweight, triglycerides etc. Polymorphism also leaves impacts on expression of genes responsible for stress, turning to cardiovascular or hypertension related problems.