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Wearable Sensor Reveals what Overwhelms You

The Q Sensor could help you manage stress by showing when you are under pressure.

What do you think most stresses you out during the day? A new type of wearable stress sensor, which constantly checks for signs of anxiety, could give you a precise answer. And it might not be what you think.

Watching you: The Q sensor tracks a person’s stress levels throughout the day. The device will go on sale this spring.

That’s what I found when I tested the Q Sensor, a device made by Affectiva, a company based in Waltham, Massachusetts. It looks like a large digital watch with no readout. A button on its surface lights up in different colors to convey the level of battery charge. Two small silver electrodes on the underside of the device continually send out a low electric current to measure skin conductance. Skin conductance rises along with physiological levels of stress, including both excitement and fear.

Over the last year, the Q Sensor has been snapped up by researchers studying everything from sleep to game design, eating habits, and brand design. Scientists are using it to tailor new treatments for autistic children; others are planning studies to see if information about stress can help treat people with drug addictions or post-traumatic stress disorder. But anyone might benefit from the information the sensor provides. Knowing our daily state of stress could help us understand ourselves and our daily lives better. It might also, perhaps, help us de-stress more effectively.

“We know stress exacerbates medical conditions,” says Rosalind Picard, a professor of media arts and sciences at MIT and lead inventor of the Q Sensor. “Stress takes a huge toll on people’s health. It’s starting to be more biologically understood.”

As I wore the Q Sensor throughout the day, I took notes on moments that seemed particularly stressful or relaxing. I assumed a meeting would cause the highest level of stress, and lunch the lowest. At the end of the day, I went to Picard’s office at the MIT Media Lab to see my readout. She explained that the raw data can be hard to understand. A peak doesn’t necessarily indicate negative stress—it could reflect excitement or an artifact like a hot room. Indeed, there were some artifacts in my data—places where the stress line mysteriously drops suddenly and slowly builds back up. This usually occurs when the sensor is bumped accidentally, Picard explained: when the sensor moves slightly, it comes in contact with dry skin. Because skin conductance goes up with heat as well as stress, an accompanying temperature sensor helps identify artifacts of another kind. And an accelerometer keeps track of the wearer’s motion, to indicate, for example, if the person is biking or running.

I wore the sensor on my left, nondominant wrist, which Picard noted moved a lot during the day, probably when I was typing. There were small spikes of stress leading up to the afternoon meeting at which I had to present ideas in front of colleagues, but surprisingly, the largest spikes occurred when I was responding to a bevy of e-mails in the morning. Picard showed me a graph of her own data recording from the day she took her son to an amusement park. Her stress levels were high on the roller coasters—but they were even higher in the morning, when she was getting everyone organized.

Stress test: This graph shows my stress levels throughout the course of a typical day. The three colored lines at the bottom are accelerometer readings; above that is a temperature reading. In the middle of the graph is the skin conductance, indicating stress levels. Sharp drop-offs (at 1:20 and 3:16) indicate that the sensor reset itself. Spikes of stress occurred in the morning, when I was multitasking and replying to e-mails.

Now that I know multitasking can be more stressful to me than a meeting, what can I do with the information? Picard is working on ways for the Q Sensor to give immediate feedback by, for example, transmitting data to a smart-phone app. The device could then issue an alert to serve as a reminder to relax.

Picard says the sensor could also help in more dire situations—for example, helping to prevent drug relapses (researchers have shown that drug cravings trigger peak levels of physiological stress). Picard is in the process of setting up a study with post-traumatic stress patients being treated for addiction at a Veterans Affairs rehabilitation center. For the study, phones supplemented with psychological surveys and positive messages will read and respond to a person’s Q Sensor.

Kevin Laugero, a professor in the department of nutrition at the University of California, Davis, studies the neurophysiology of eating and the ways in which stress can affect decision-making related to food intake. He is using the Q Sensor in combination with other tools to look into whether preschool children are more likely to eat a snack when their stress levels are high. In the past, Laugero and his team had to measure stress by taking samples of saliva and checking the levels of the stress hormone cortisol, a process that yielded intermittent rather than continuous data.

The Q Sensor has business applications as well. “It is becoming an active part of our diagnostic set,” says John Ross, CEO of Shopper Sciences, a marketing and advertising firm that helps companies understand consumer behavior. When a fast-food company wanted to know why customers were not returning to its restaurants despite reporting overall satisfaction with the food and atmosphere, Ross used the Q Sensor to solve the mystery. It turns out it was the process of selecting the food from the menu that was frustrating customers, says Ross. 

Ross is planning to build an extensive Q Sensor database to learn about patterns in larger groups and predict consumer reactions to different situations. “Our goal is to have the largest database of shopper physiological response of any company in North America by the end of the year,” says Ross. 

Picard hopes the device could eventually have broad appeal. A lot of people simply don’t know or believe they’re stressed. “This is technology that can transform people’s ability to understand themselves and participate in the process of health and medicine,” she says. 

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