CHICAGO — Is there a way to tell when it's morning in your body?
Researchers at Northwestern say they have found a new way to gauge what time it is on someone's internal biological clock.
A new study released Monday in the Proceedings of the National Academy of Sciences of the United States of America journal detailed a blood test researchers say can roughly read someone's internal time clock. In other words, it can tell if it's 6 a.m. in your body while it's 4 p.m. on a real-time clock.
The new test, called TimeSignature, measures 40 different gene expression markers and can be taken any time of day.
Rosemary Braun, the study's lead author and an assistant professor of biostatistics at Northwestern University's Feinberg School of Medicine, said the blood test can assess a person's biological clock to within an hour and a half.
Researchers first drew subjects' blood and examined which genes were higher or lower during the day. By monitoring genes of people whose body clocks were aligned normally, they were able to establish an algorithm that could predict the time of day based on these patterns.
Kenneth Wright, professor of integrative physiology at the University of Colorado at Boulder and director of its Sleep and Chronobiology Laboratory, said this is an advance toward better understanding biological clocks.
"This is a very important first step," he said. For example, in his lab, he has patients come in for at least seven hours and as many as 24 hours, checking saliva or blood every 60 or 90 minutes. This would greatly reduce the amount of time and tests needed, he said.
"It's a significant advance in terms of trying to develop tools so we can actually more easily determine circadian time, or biological time," he said.
Researchers have long sought to better understand circadian rhythms, which are linked to a variety of body systems.
"Everything from when you feel sleepy to when you feel hungry to when your blood pressure rises and falls," Braun said. "With it controlling so many different things, it's unsurprising that it also has a really big impact on health."
Disruption of an internal clock can predispose someone to a range of diseases -- diabetes, obesity, depression and heart disease have all been identified with connections to misalignment in circadian rhythm.
The impact of a way to better, and more quickly, understand a patient's body clock could have implications for medication dosage and even predicting disorders and risk factors. Braun hopes this new test will help researchers examine the impact of misaligned clocks in diseases from heart disease to Alzheimer's.
Medications for everything from blood pressure to chemotherapy treatments have their best impact at different times, she said. "With a simple blood test, your doctor might be able to tell you, now is the best time for you to take your blood pressure," she said.
Of course, it could also help better treat people with disrupted sleep patterns.
"You can imagine that somebody might come into their doctor's office after a sleepless night because they have a new baby or they do shift work," she said.
The researchers note that no method so far, including theirs, has been tested across a broad range of conditions and diseases.
"More research is needed," Braun said. "What we envision down the road, ultimately, is this being used as a diagnostic and as a monitoring mechanism."