Standards Development

Scope

This standard specifies terms and measurement methods for stress of wearable devices having a skin conductance sensor, a photoplethysmograph sensor, or a respiration sensor. The object of this document is to define and provide the standard test methods to evaluate the capability of the wearable device to determine whether the wearer of the device is str essed or not. This standard test method is limited to wearable devices worn on the wrist or on the torso.

The test method consists of a test protocol that is used on a number of human test subjects in a controlled setting. The human test subjects are to perform a number of tasks designed to obtain a baseline, induce relaxation or to induce moderate psychologic al or physical stress.

Salivary cortisol is sampled to obtain a ground truth for the induction of stress by the protocol.

This standard defines 1) terms related to stress and 2) stress indicators that are relevant for stress monitoring technologies. Additionally, it describes 3) stress assessment protocols and data collection for the measurement of stress by consumer stress monitoring technologies. This standard also references definitions and creates performance criteria for consumer stress monitoring technologies that use Heart Rate (HR), Heart Rate Variability (HRV), and related measures in the measurement and application of stress metrics.

Purpose

Researchers, scientists and experts have been trying, with limited success, to come to an agreement on the definition of stress. Canadian physician and medical researcher Hans Selye labored all his life to find a satisfactory definition of stress. In attem pting to extrapolate his animal studies to humans so that people would understand what he meant, he defined stress as “The rate of wear and tear on the body”. Since that time, the scope of the sources of such stress has grown to include both physical and cognitive/emotional sources.

The purpose of this standard is to define stress within the limited context of wearable consumer monitoring solutions. The purpose of defining stress in this context is to provide parameters, and limits, under which a Product can be expected to measure str ess and report useful information to a user of the solution. While a perfect measurement of stress would include measurable changes to physiological variables (such as heart rate and sleep patterns), and subjective responses obtained though accepted psychological instruments, for the purpose of this specification only metrics related to stress responses that can be measured using a wearable, consumer -grade solution will be included.

The need and justification for developing this standard was agreed to when PWI 124 -9 was accepted. There are many devices used by consumers and sold by manufacturers, and a standard to help improve the accuracy of reporting will serve this market.