Feeling tense? Headaches? Yelling at friends for no reason? Arms tired from gripping your steering wheel too tight?
Stress is uncomfortable — that’s obvious. And for decades many of us have tried various remedies, from exercise and meditation to “unwinding” over drinks or actually taking medication. But now scientists are starting to understand that dealing with stress is more than something we may want to do to ease tense muscles. Stress, over time, is now believed to have debilitating effects that could shorten our lives.
But how do you, or your doctor, know when the stress you have is too much?
A group of scientists from Florida International University in Miami and North Carolina State University are working on a tiny sensor to measure the body’s production of the hormone cortisol, which is the main signal that we’re stressed out.
It’s a new technology that could eventually allow a wearable strip to track your stress levels and help alert doctors when you’re dangerously tense.
One application for the device may be helping medical professionals track the needs of people with post-traumatic stress disorder; another might be an added test for heart attack risk.
And it’s not too far of a leap to imagine employers being able to track levels of tension in people in dangerous, high-stress jobs, such as law enforcement officers, pilots or air traffic controllers. Overstressed workers could more easily be given help if their cortisol levels are known.
Doctors have long been able to measure the body’s production of cortisol in the lab by collecting saliva, blood or a hair sample.
But that gives a one-time snapshot of someone’s cortisol levels — and many of us stress out when we go to the doctor, especially if they're pricking us with a needle to draw our blood — giving a false reading. A wearable sensor could create a record of stress over time. That way, you, or your doctor, could deal with stress before it’s a problem.
“The focus is going to be on managing wellness, rather than managing illness,” said Dr. Shekhar Bhansali, an electrical and computer engineering professor at FIU, who is leading the engineering side of the team working on the technology.
Medical scientists are more and more interested in developing a range of sophisticated sensors that do more than measure things like heart rate or simple things like movement — something many of us already do through devices like a Fitbit.
“Fitbit is great,” Dr. Bhansali said. But it’s limited. “You really want to know the biology, the physiology of what's going on in the body.”
The idea of getting a sense of that physiology through wearable mini-computers is part of a growing belief in medicine that the future of monitoring patients may be outside of hospitals and doctors’ offices — away from the expensive machinery currently used — once chemicals or metabolites in the body can be easily measured.
They started using cortisol as a biomarker while testing whether a device could easily pull sweat off the skin and past a sensor.
“We had been trying to optimize sensors, and we were just using this as a model marker,” he said. Cortisol seemed like an interesting substance — in part because of lots of talk about post-traumatic stress disorder, he said.
Dr. Bhansali, whose background is in aviation and other types of engineering, found out that his work could have broad implications only after talking almost off-handedly with people in medicine.
“They said, ‘You can really do this?’” Dr. Bhansali recalled.
Well, soon they're going to find out. Dr. Bhansali hopes to do tests in the spring.
“What we are working on, and I think this will be done by May, is seeing whether you can passively pull sweat in and bring it across the sensor,” he said.
In addition to those with PTSD, Dr. Bhansali says better measurements of cortisol could also help pregnant women, and maybe even help doctors better understand moody teenagers.
Dr. Bhansali's group is working with the N.C. State-based ASSIST, Advanced Self-Powered Systems of Integrated Sensors and Technologies, which develops wearable nano-devices and sensors for health purposes. But they aren’t the only ones working on the new idea.
The Novel Devices Laboratory at the University of Cincinnati and scientists at Wright Patterson Air Force Base near Dayton, Ohio, are also working on wearable sensors that use sweat to measure body chemistry, according to IEEE Spectrum. Sweat contains several biomarkers that can be used to detect various anomalies — doctors have used perspiration to screen for cystic fibrosis for years.
That group is in the process of starting human trials on flexible, wearable patches to see if they can successfully wick sweat from the body and measure various ions, hoping to predict muscle damage in athletes, among other things.
Besides cortisol, sweat could provide information on a number of biomarkers.
Researchers at the Cincinnati group also hope one day that glucose might be measured this way, which would be helpful to diabetics. Researchers at the University of California San Diego have used sweat to measure changes in lactate, useful for predicting when an athlete is exhausted. The Air Force is hoping to be able to measure certain biomarkers that can tell them not just how stressed pilots are, but how alert they are as well.
Dr. Bhansali says that making it easier to measure certain biomarkers may make it more likely that patients keep to a monitoring regimen. People who don’t like to get blood drawn may not keep appointments.
“We don’t mind as much slapping sensors on ourselves,” he explained.
But it’s serious medical stuff that has the potential to revolutionize the monitoring of certain types of disorders, and maybe even the prediction of disease.
“The next frontier is going to be metabolite sensing,” Dr. Bhansali said. “It's just a matter of time.”
Top photo caption: The latest version of the cortisol sensor. (Photo courtesy of Florida International University)