The Daily Camera: A single blood draw can be used to determine someone’s internal circadian clock, information that’s useful for everything from treating cancer to getting better sleep, according to new research from the University of Colorado Boulder.

Studies have shown that looking at a person’s circadian rhythms, the name for the body’s internal sleep-wake cycle that repeats every 24 hours, can be used to improve outcomes for medical treatment like prescription drugs, undergoing chemotherapy and even surgery.

Before now, patients would need to live in a lab in dim lighting for 24 hours and give saliva blood samples every hour to measure their melatonin levels in order to determine their individual circadian clock.

CU Boulder and CU Anschutz researchers found that looking at metabolites — things like amino acids and vitamins that are the byproducts of metabolism — in someone’s blood can provide similar information.

Researchers recruited 16 people to live in a sleep lab 24 hours a day for two weeks, controlling their sleeping and eating schedules as well as the light levels in their rooms. By looking at metabolites as well as melatonin levels, researchers were able to identify metabolites that are related to circadian rhythms and predict the circadian phase within about an hour of the more involved test, according to the study published in the Journal of Biological Rhythms.

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