Cardiovascular Risk Factors / Disease States

The Internal Body Clock and Cardiovascular Disease

The Internal Body Clock and Cardiovascular DiseaseCardiovascular disease (CVD) is one of the UK’s biggest killers. In 2010 almost 180,000 people died from the complications arising from CVD; approximately 80,000 of these deaths were caused by coronary heart disease and around 49,000 resulted from stroke. As well as the high death rates associated with CVD there are the costs of maintaining an aging population with a proportion suffering with various facets of CVD. In 2011 alone around 292 million prescriptions were issued for CVD in England (1).

The circulation of blood clots is a major cause of myocardial infarction (heart attack) and ischemic stroke. These act detrimentally by blocking either the blood flow within the heart or the brain. Plasminogen activator inhibitor-1 (PAI-1) is known for inhibiting the breakdown of blood clots. As a result, greater concentrations of PAI-1 are associated with a higher number of heart attacks or ischemic strokes.

New research published in Blood (November 2013) focused on measuring levels of PAI-1 to determine if the previously observed high morning levels were due to environmental factors or simply due to circadian rhythms. This was achieved by taking a group of twelve healthy adults and placing them into laboratory controlled conditions – ensuring that participants were desynchronised from their usual daily behaviour and environmental routines.

It was found that the body’s circadian rhythm circulated high morning levels of PAI-1 with a peak at approximately 06.30, (in a regular sleep/wake cycle). Due to participants being tested outside of their usual routines, researchers believe that the internal body clock and circadian rhythm are independent from any external influences (2).

This promising study could help to identify why ‘at risk’ individuals are more likely to suffer from cardiac events in the morning. Although this has highlighted the 24-hour cycle within healthy adults, researchers have noted that follow up studies are required to test vulnerable adults suffering with conditions such as obesity, diabetes or CVD.


1.    Coronary heart disease statistics A compendium of health statistics 2012 edition. British Heart Foundation Health Promotion Research Group Department of Public Health, University of Oxford.

2.    F. A. J. L. Scheer, S. A. Shea. Human circadian system causes morning peak in pro-thrombotic plasminogen activator inhibitor-1 (PAI-1) independent of sleep/wake cycle. Blood, 2013; DOI: 10.1182/blood-2013-07-517060


If you are studying the effects that PAI-1 has on the cardiovascular system it would be of benefit to utilise Biochip Array Technology. This novel and patented method was developed by Randox Laboratories and facilitates rapid and accurate multi-assay results. The unique ‘Metabolic Syndrome Array I’ allows for the multiplex testing of a single sample for nine biomarkers commonly associated with cardiovascular disease, obesity and diabetes.

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