The Moodmetric smart ring measures stress as a physiological phenomenon. It is a user-friendly way to capture electrodermal activity (EDA), which tells about activation of the sympathetic nervous system.
This series of articles is about stress and the ways to measure it. Parts 1 and 2 describe the fight or flight reaction and how the body reacts to chronic stress. How the electrodermal activity is connected to stress, is presented in part 3. In this article we explain the Moodmetric measurement and how to interpret the data.
How is the Moodmetric measurement done?
The Moodmetric smart ring measures stress as a physiological phenomenon. This is done by interpreting electrodermal activity that tells about the sympathetic nervous system activation.
Increased sympathetic nervous system activation makes sweat glands work harder. This can be seen in greater conductance of the skin.
Conductance measurement requires two electrodes of conductive material. The band of the Moodmetric ring works as a set of electrodes. It consists of two silver coated steel rings and an insulator band in between them.
The measurement accuracy is the greatest on the palm side of the hand
To achieve a good and steady reading, the electrodes need be in contact with an area of the skin where the eccrine sweat gland density is high. This density can vary from 400/cm2 on the palm of the hand to about 80/cm2 on the upper arm.
Accurate skin conductance measurement can thus be done from the palm side of hand. A finger ring has an optimal position from the accuracy point of view and the Moodmetric ring is a ring for this reason. The actual point of measurement is on the inside of the finger and at best the signal is completely unbroken.
The Moodmetric smart ring stores measurement data continuously
The ring measures continuously and stores the data inside the ‘stone’. The mobile app does not need to be turned on or open, nor the phone near the ring. When the app is activated and the calendar icon chosen, the ring sends the data to the app via a bluetooth connection. The measuring and data storing to the ring continue immediately. The real-time signal – in other words, the ongoing measuring in process – can be observed at any time on the app.
Research by the Finnish Institute of Occupational health (2015) shows that the signal of the Moodmetric ring is comparable to that of a laboratory device. The ring is suitable for field studies too.
The Moodmetric signal is real time
The Moodmetric signal is the violet curve on the mobile app that can be observed in real time. It is the raw measurement signal, autoscaled in order to have the whole amplitude visible even during strong reactions.
The curve enables the analysis of single reactions. Even a thought – excitement, idea, awe – can cause a peak and is registered with only a 1-2 second physiological delay.
Interpreting the raw signal requires expertise in the measurement method and understanding of the possible sources of error.
The Moodmetric stress measurement data
A laboratory setting usually studies the electrodermal activity (EDA) raw signal. This is difficult to interpret and requires an expert to perform the study. Strong reactions can easily be spotted on the curve, but mathematical methods are needed to gain further insight.
The Moodmetric level has been developed to provide accurate EDA measurement for field setting. Another aim is to provide data that is easy to interpret for anyone.
The Moodmetric level makes the data easy to interpret
The algorithms count an index, the Moodmetric level (named MM Level on the app) of 1 to 100 so that 1 is the lowest the person can reach. This is possible, for example, in deep sleep. 100 is the maximum level of arousal, strongest possible reaction. Since we are all individuals, the Moodmetric measurement method is designed to find the minimum and maximum levels of each person within the first 12 hours of taking the ring into use. This is called the calibration period. The ring should be re-calibrated when handing it over to another user.
The MM Level on the app and the raw signal (the violet curve) being drawn, show the person’s ongoing activity and level of excitement. The MM level does not indicate single reactions, but changes fast if the arousal level of the person increases or decreases rapidly. The raw signal indicates even single reactions.
Benefits of indexed data
When calculating the MM Level, the algorithms minimize the effect of finger movement and skin moisture. The MM level is comparable between users. If two persons are placed in the same environment and situation, it is possible to observe which one is calmer.
There is no momentary optimal value
It is normal for the Moodmetric level to fluctuate between 1 and 100 during the day. No momentary value is good or bad.
It is equally important to acknowledge that the Moodmetric measurement does not tell whether a reaction is positive or negative. The Moodmetric smart ring is not a detector of emotions as such.
The fluctuation of stress levels is different for everyone
There are people who react fast and strong, while others respond more calmly. For instance, a person doing work that requires much concentration over long periods of time might have low MM levels throughout the working day.
The levels can be high due to excitement and energy, or low due to intense concentration. All this is positive. The levels might also be high due to pressure and lack of control at work. Low figures in turn can tell of boredom or even depression. For an accurate assessment, the measurement data always needs to be complemented with the ring wearer´s own perception of the situation. Only the person in question knows whether a set 100 tells about excitement or irritation.
The 24-hour MM average level is what it’s all about
The Moodmetric smart ring measures the reactions of the sympathetic nervous system on a scale of 1 to 100. When the 24-hour average value is around 50, there is enough recovery in correlation to the load.
Fluctuation of the MM levels during the day can vary much between different individuals. High daily figures are no cause for worry if the person feels energetic enough and has a restful night: It is the 24-hour MM average level that counts. The same goes for someone whose MM levels don’t peak during the day.
The point is demonstrated in the graphs below: Two persons have exactly the same 24-hour MM average level of 46, which signifies a good balance between rest and activity, but their autonomous nervous systems are activated in different ways and by different stimuli during night and day.
The more you use the ring, the more information you gather to help you adjust your behavior. It is therefore recommended that the ring is worn also during nighttime.
The Moodmetric Level 50 tells of balance of the autonomous nervous system
Feedback from users of the Moodmetric smart ring indicate that the MM level correlates with a user’s own perception of their situation. If the 24-hour average is around 50, the energy levels are normal. Values over 50 for long periods of time go hand in hand with the feeling of being overloaded; cracks in one’s well-being begin to show. Very low daily figures, on the other hand, might be a sign of depression.
The Moodmetric measurement helps the user to gain balance between load and recovery. The sources of stress and ways to recover differ from person to person. For this reason, the measurement data should never be examined in isolation, but further self-assessment by the individual is required. The Moodmetric smart ring and app are tools for a person seeking more balance in their life.
The complete set of 5 articles explains the Moodmetric measurement, science behind and the applications:
- Part 1: Fight or flight response
- Part 2: Chronic stress
- Part 3: Tools for long term and continuous stress measurement
- Part 4: Measuring stress with the Moodmetric smart ring
- Part 5: Moodmetric measurement in preventive health care