Mental Health

Measuring stress by HRV and EDA


EmoGraphy provides insight in how we respond to stress. Humans respond to stress in two ways; an immediate response to the stressor (adrenaline release) and a slower response (cortisol release) to recover from that stressor. Stress has a direct impact on our cognitive performance. High cortisol levels may negatively affect cognitive performance such as contemplation, strategic thinking and memory function. Low levels are thought to increase fatigue by making tasks appear tougher, and limiting endurance of sustained physical and mental activities.

EmoGraphy provides detailed insights in this mechanism by displaying stress levels in real-time andcalculating the related cognitive functioning of the brain – the CognitiveZone - that is impacted by cortisol. Through these measurements and calculations, EmoGraphy can also predict changes in cognitive abilities up to an hour ahead (assuming the user performs similar activities).

EmoGraphy is based on skin conductance (EDA); an accurate measurement of sympathetic nervous system activity that reflects the body’s so-called fight or flight response. The Cognitive Zones help the user to understand how to optimize his/her cognitive performances and avoid under- and over-stimulation.

    • Over stimulated zone
      Decreased cognitive performance; strategic thinking, memory, etc. - you might want to do a relaxing exercise to reach the balanced zone for optimal performance
    • Balanced zone
      Optimal cognitive performance – to stay in this zone take regular breaks
    • Under stimulated zone
      Enhanced perception of effort, reduced endurance of mental activity – you might want to take a walk or activity to stimulate yourself to reach the balanced zone

Stress Level

Stress Level reflects the immediate response to a stressor. It indicates the amount of physical (strong exercise, spicy food, or the temperature) and emotional stress of the user at present time. 

Cognitive Zone

Cognitive Zone is based on the slower response (cortisol release) to a stressor. By remaining in a zone of optimal emotional stimulation, you can avoid both drowsiness and too much stress. This is the objective of Cognitive Zone. The Balanced Zone represents the area of emotional fitness, essential for healthy lifestyle and optimal cognitive performance.

    • Cognitive Zone is the current cognitive zone at present time.
    • Cognitive Zone in One Hour is a prediction of the cognitive zone in one hour assuming the user performs similar activities as at present time
    • Predictive Cognitive Zone is the next predicated cognitive zone in a number of minutes given by the Predictive Cognitive Zone Transition Time.
    • Predictive Cognitive Zone Transition Time is the time to reach the next predicted cognitive zone

Cortisol Contribution

The Cognitive Zones are derived from the estimated Cortisol Contribution which is the amount of cortisol that can be accounted for by stress. Cortisol is the most accurate measure of stress but it can only be measured via blood, hair or saliva samples. By calculating the cortisol contributions, Philips is able to determine the easy-to-understand CognitiveZone.


Corsano and Philips are planning to run pilots at Care Organizations monitoring patients and staff with CardioWatch 287-2. Healthcare work has been associated with a considerable level of stress and anxiety leading to exhaustion, difficult triage decisions, separation from families, stigma, fear of being infected, fear of infecting their beloved ones, and pain of losing patients and colleagues. CardioWatch 287-2’s accompanying application shows Healthcare workers their stress level up to one hour in advance. This enables them to adjust.