Circadian rhythm was known to ancient man from the time of Homoerectus and Homosapiens who use to have intercourse in the early morning hours, before going for hunting to forests, which became a circadian rhythm. Increased secretion of testosterone is reported in the morning. The supra-chiasmatic nuclei (SCN) and clock gene contribute to the coordination of the circadian rhythms' phase and amplitude, in every day life. The SCN are influenced by the daily alteration between light and darkness with increased plasma melatonin concentrations released by the pineal gland in the night. A clinical event occurs when our neuroendocrine time structures (chronomes) are not able to cope with the adverse effects of stimuli from within or from without, acting, e.g., via the sympathetic nervous system. Triggering of the neuro-endocrines by environmental factors may activate the pineal gland, pituitary functions and adrenal secretions, resulting in adverse effects on circadian variations of various biomarkers of health responsible for cardiometabolic diseases (CMDs) including adverse effects on heart rate variability (HRV) and blood pressure variability (BPV). Frey considered the mean distribution of deaths along the scales of the day and the year. In one industrial population, Pell and D'Allonzo, discussed time-macroscopically the occurrence of a peak in the morning hours in a study of acute myocardial infarction (AMI), a proposition also ascertained and extended to the yearly pattern time-microscopically. The subsequent reports from the Soviet Union and the extensive data by WHO in the report of myocardial infarction Community Registers from 19 European centers demonstrated a peak incidence of onset of chest pain due to AMI from 8.00 to 11.00 AM.In a more recent Mechanism of Acute Myocardial Infarction (MAMI)study by Singh et al,, among 202 AMI patients, the incidence of onset of chest pain was highest in the second quarter of the day (41.0%), mainly between 4-8 AM, followed by the 4th quarter, usually after large meals (28.2%).Emotion was the second most common trigger (43.5%), which was commonest in the patients with onset of chest pain in the second quarter of the day (51.8%).Cold weather was a predisposing factor in 29.2% and hot temperature ( >40°C) was common in 24.7% of the patients.A large meal, especially large breakfast in the morning was an important trigger of AMI in this study,which poses the possible that Americans can prevent heart attacks if they do not eat breakfast or prefer a small superfoods breakfast containing walnuts,almonds,raisins and yogurt which are known to be protective against CMDs.Blood pressure is usually lower during the night, starts increasing before awakening, and remains high during the day-time,mostly in the second quarter of the day.Circadian rhythms of various biomarkers of diseases and their mechanisms have been described by various workers.It is possible that circadian rhythms could be a new target for treatment in the management of CMDs.