What is electrodermal activity?
Electrodermal activity (EDA) is a biomarker of sympathetic nervous system activation and is considered to be one of the most valid markers of emotional arousal, or stress. During high levels of ‘emotional arousal' such as stressful states, sweat secretion is intensely activated. This causes skin impedance or skin conductance to increase.
One of the largest challenges associated with the application of EDA to real life, is the process of defining a stressful, sweat-producing ‘event' as either a positive or negative stressor. Exciting events such as your favourite football team winning a match can generate a similar physiological reaction to negative events like shouting with your partner. In these cases, algorithms and other indicators become very useful in unscrambling the stress responses.
Combining EDA readings with other information
Skin temperature is also a useful indicator of stress, for example skin temperature decreases during stressful events. Therefore, combining EDA with skin temperature could provide the final piece of information useful in distinguishing between positive and negative events.
However, many wearable devices do not accurately measure skin temperature, but what they do measure is HRV. HRV is considered to also be a strong indicator of stress, and so combining HRV measurements with EDA scores can provide robust stress information.
What can we do with data on stress levels?
Whilst the most common application of EDA is to track a person's stress levels, there are many other novel applications that can be developed on top of it ranging from athletics, to neonatology, to pharmacological monitoring, to personal digital health.
This is because sweat contains many of the same biomarkers, chemicals, or solutes that are carried in the blood which can provide detailed information enabling the diagnosis of ailments, health status, toxins, performance and other signs.
An interesting application was explored by Pohorecky (1991) who found that a high level of stress may lead to an excessive intake of alcohol - EDA can be used to monitor blood alcohol levels and hence, help to combat alcohol abuse disorders.
Through the Terra API, we provide connections to a range of different devices that contain EDA sensors.
Below is a list of the wearables that contain EDA sensors today:
- Fitbit Charge 5, Sense
