Scientists develop blood test to measure body’s circadian rhythm

August 2, 2021

The human body’s internal clock, or circadian rhythm influences all matters related to health and well-being, including the optimal time to exercise or take medication; but measuring a person’s individual circadian rhythm has so far been, unfortunately, tedious. However, scientists at the University of Colorado (CU) Boulder, US, have found a way to determine an individual’s circadian rhythm by analysing a series of molecules just with a simple blood test.

According to then Assistant professor of Integrative Physiology at CU Boulder, Christopher Depner, the discovery “is an important step forward in paving the way for circadian medicine, for personalised medicine,” where treatments and wellness regimes are better tailored to individuals.

Researchers have long known that a central “master clock” in a region of the brain called the hypothalamus helps to regulate the body’s 24-hour cycle; nearly every tissue or organ in the body is synced with that master clock as well – it affects everything from hormone secretion to fat metabolism to organ function. The differing circadian rhythm between individuals is also why some people are night owls and others are early risers, or why others enjoy an afternoon nap on the couch.

Needless to say, disruption to this circadian rhythm can increase the risk of disease.

“If we can understand each individual person’s circadian clock, we can potentially prescribe the optimal time of day for them to be eating or exercising or taking medication,” said Depner.

Instead of the dim-light melatonin assessment – the gold standard for measuring the body’s internal clock – scientists at CU Boulder chose to take a different approach referred to as “metabolomics.” Here, the scientists enlisted 16 volunteers who spent 14 days in a sleep lab and provided hourly blood tests for analysis. They simultaneously assessed the levels of 4,000 different metabolites in their blood, including amino acids, vitamins and fatty acids, associated with each individual’s circadian clock using a machine learning algorithm – this “molecular fingerprint” could accurately predict the circadian phase from a single sample.

While the technique currently needs to look at some 65 metabolites, the scientists say it should be narrowed down further to make it commercially viable. Further, there are other problems to solve before the technology moves beyond the lab, such as the fact it was far more accurate when the subjects were well rested and hadn’t eaten recently.

But the study is a critical first step, said the Director of the Sleep and Chronobiology Lab at CU Boulder. Other research, including some from Wright’s lab, is exploring proteomics (looking for proteins in blood) or transcriptomics (measuring the presence of ribonucleic acid or RNA) to assess circadian rhythm(s).

Tags: blood test, health, human body’s internal clock, scientists