Stress related to our mental well-being, including that associated with depression, anxiety, and PTSD, is difficult to measure in practice. Levels of cortisol, a steroid hormone, are closely linked to changes in one’s mental state and blood tests are available to measure cortisol. But a blood test can raise a person’s stress level itself and it can’t be done frequently, nor without a medical professional. Now researchers at Caltech are reporting on the first noninvasive, wearable sensor that can detect…
