PART 4: Measuring stress with the Moodmetric ring and understanding the data

The Moodmetric stress measurement data is real-time and tells of the fluctuating stress levels also in long term.

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. Methods for long-term monitoring are presented in part 3. In this article we explain the Moodmetric measurement and how to interpret the data.

How the Moodmetric ring worksThe Moodmetric smart ring measures electrodermal activity. It detects skin conductance with the band of the ring that works as a set of electrodes. The band consists of two silver coated steel rings and an insulator band in between them. 

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. The ring form was chosen to achieve the best possible accuracy generated by the Moodmetric sensor. The actual point of measurement is on the inside of the finger and at best the signal is unbroken.

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 in 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 Moodmetric ring real time curve

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

The raw signal for electrodermal activity (EDA) is difficult to interpret. 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 data that is easy to interpret. The algorithms count an index from 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 recalibrated when handing it over to another user.

The Moodmetric real time viewThe MM level on the app, both the numeric value and the curve being drawn, show the person’s ongoing activity and level of excitement for the past few minutes. The MM level does not indicate single reactions, but changes fast if the arousal level of the person increases or decreases rapidly. Increasing is first visible in the growing amplitude and the raising trend of the Moodmetric curve, then in the higher numeric value for the MM level.

It is easy to get to 100. The challenge lies in working out the ways in which to get the MM level as low as possible.

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 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, creative people are often very susceptible to stimuli, which can translate into high and fluctuating MM levels. In contrast, 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.

A successful team is heterogeneous also by the way they react

On average, it is productive at work to have people of different temperaments. Depending on the work, of course, a team consisting only of individuals with either a very mild or a very strong natural way of reacting is probably not as productive as a more heterogeneous team.

The Moodmetric stress measurement data increases our understanding of the different ways in which people react to various situations. This is important from the point of view of health and well-being; to challenge and grow, we should look within and learn from our experiences rather than compare ourselves to others.

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.

Measuring stress with the Moodmetric ring and understanding the data

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.

Feedback from users of the Moodmetric 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 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:

  1. Part 1: Fight or flight response
  2. Part 2: Chronic stress – The brain concludes that we are continuously in danger
  3. Part 3: Tools for long term and continuous stress measurement
  4. Part 4: The Moodmetric ring stress measurement and understanding the data
  5. Part 5: The Moodmetric measurement in preventive occupational health