How do smartwatches measure stress?

In this article we will answer the question “How do smartwatches measure stress?”

We will also briefly discuss whether smartwatches can accurately measure stress, what stress is, how it impacts one’s life, and what one can do to manage stress. 

How do smartwatches measure stress?

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Smart watches measure stress level by measuring the length of time between heartbeats, this measurement is called Heart Rate Variability. 

Heart Rate Variability was first described by Rev. Stephen Hales in 1773. He noted that the interval or the time between each heartbeat differs according to a person’s breathing and this mechanism appears to be under the control of our autonomic nervous system. 

When a person inhales the HRV shortens and lengthens every time a person exhales. If a person is under stress because of exercise or a particular trauma, the HRV shortens and he/she will have a low heart rate variability.

Basically, the lower the variability between beats, the more stressed you are. So what the watch and apps do is measure the time it takes between two heartbeats, measuring HRV.

By measuring the frequency at which the heart rate varies, and doing some calculations on that data, the level of stress of an individual can be determined.  

The HRV data are then stored and continuously compared in real-time to produce a pattern from which conclusions about a person’s stress levels are drawn.

The lower the HRV value that the smartwatch identifies, the higher the stress is. Research finds that if you measure Heart Rate Variability continuously for 24 hours, you can detect differences between healthy subjects versus subjects who are under stress- so there is empirical data that backs the mechanism of the smartwatch health app.

While it can measure whether you are highly stressed or not, what the app cannot do is determine what the stress is caused by- it could be a result of you missing your smartwatch while training or running. 

However, if you have not engaged in activity or exercise and the HRV is still low, it could be an indication of mental and emotional stress. 

Why is it important to measure stress?

High levels of stress can lead to deteriorating physical and mental health. 

Thus it is very important that we keep track of our levels of stress so that we can also adapt various strategies and include various changes in our lives in order to reduce or remove stress and stressors. 

Stress is our natural response to the demands around us. 

Stress is actually a good thing since it motivates us to access and act and it serves as a defence against dangers and predators. Thus, it has a positive impact on us at a healthy level. 

However, in today’s day and age we are less likely to be affected by a predator. Stress arises when we are unable to meet the demands of our day to day lives. 

That is, when we exhaust our mental, emotional, and physical resources to  execute the demands of our jobs, relationships, as well as meet our needs.

High levels of stress can lead to deteriorating physical and mental health. It can cause symptoms such as:

  • Headache
    Tiredness
  • Disturbed sleep schedule
  • Higher than normal blood pressure
  • Faster ageing
  • Heart illness 


When an individual is under constant stress and high levels of chronic stress due to their lifestyle or their environment, it can lead to high levels of cortisol.

High levels of cortisol have been connected to mental health conditions such as anxiety disorders as well as depression which are serious mental health disorders which can significantly impact the quality of life of an individual. 

By keeping track of our levels of stress, we can be vigilant against activities and lifestyles that can increase stress or cause more stress while also helping us to remove or replace stressors with more adaptive measures such as mindful living, relaxation, exercises etc. 

How accurately do smartwatches measure stress?

Stress monitoring on the Smartwatch can only be effective if the equipment used to collect the data is dependable. 

Smart Watches use Heart Rate Variability, or HRV, to measure stress and it does not rely on any other measurements or circumstances that a doctor might observe and assess. This means that Smart Watches are only as accurate as the sensor allows it to be.

To ensure that your smart watch is accurate you must ensure the accuracy of your fitness tracker by comparing the results to your doctor’s prescription.

There are some factors that negatively impact the accuracy of the smart watches readings of stress levels. These factors include:

  • If the sensor is not working or reliable, it can cause problems or inaccurate reading. To check the accuracy of your sensor on the Smartwatch, you can check it against the readings of a doctor or professional tools used to calculate HRV. 
  • Your readings can also be disrupted if you check your measurements lying down or in other positions other than sitting straight up,
  • Consumptions of drugs and alcohol including caffeine can also cause disruption and inaccurate readings since they are recognised as depressants and stimulants respectively that can impact heart rate.
  • Exercise can also impact stress scores, levels increasing when you engage in strenuous exercise. 
  • Lifestyle and diet can also impact your stress scores, with lack of proper sleep, healthy diet, and a healthy routine can negatively impact your well being and increase stress scores. 
  • Short-term illness like a cold or the flu as well as longer-term health conditions can have an impact on the stress scores including your age. 

What Are the Causes of Stress?

Stress is our natural response to the demands around us. 

Stress is actually a good thing since it motivates us to access and act and it serves as a defence against dangers and predators. Thus, it has a positive impact on us at a healthy level. 

However, in today’s day and age we are less likely to be affected by a predator. Stress arises when we are unable to meet the demands of our day to day lives. 

That is, when we exhaust our mental, emotional, and physical resources to  execute the demands of our jobs, relationships, as well as meet our needs

The National Institute of Mental Health (NIMH) has recognized three types of stressor:

  • routine stressors that are a result of day to day demands. 
  • sudden, disruptive changes, such as death or loss.
  • traumatic stress, which can occur due to extreme trauma caused by an assault, an environmental disaster, or war.

Common major life events that can trigger stress include:

  • Lack of work-life balance
  • Poverty
  • Bereavement and loss/death in the family
  • Family problems
  • illness
  • Environment changes
  • Relationship problems
  • Pregnancy issues or infertility
  • Changes in personal roles- eg: Parenthood
  • uncertainty 
  • Traumatic event
  • Stressful work environment
  • Phobias

What are the effects of stress?

If your stress is acute, meaning that you’ve been stressed out for a short period of time due to a small issue such as handing in a report or finishing a project before deadline, you may start to notice some of these physical signs of stress such as:

  • Headache
  • Fatigue
  • Difficulty sleeping
  • Difficulty concentrating
  • Upset stomach
  • Irritability

But when the stress becomes long-term and is not properly addressed, it can lead to physical, emotional, and mental problems such as:

  • Depression and anxiety
  • Insomnia
  • High blood pressure
  • Abnormal heartbeat (arrhythmia)
  • Heart disease
  • Heartburn, ulcers, irritable bowel syndrome
  • Weight gain or loss
  • Changes in sex drive
  • Fertility problems
  • Skin problems such as acne, eczema, and psoriasis

These effects of stress can negatively impact an individual and lead us to exhaust our mental, emotional, and physical resources to execute the demands of our jobs, relationships, as well as meet our needs.

How to Manage Stress effectively?

Managing stress can be done individually as well as with assistance from a mental health professional. 

Treatments to manage stress include:

  • Self-help lifestyle changes in diet, exercise, activities, and relationships. 
  • Therapy and counselling which help people develop self awareness and also help them make lifestyle changes that can help them manage stress.
  • Medication, though doctors will not usually prescribe medications for coping with stress, unless they are treating an underlying mental health condition that is causing the stress. 

Lifestyle changes that can help manage stress includes:

  • Exercise including engaging in breathing and relaxation medication and techniques to slow down heart rate and promote rest. 
  • Reducing the intake of alcohol, drugs, and caffeine
  • Eating a healthy, balanced diet containing plenty of fruit and vegetables can help maintain the immune system at times of stress. 
  • Organising a daily to-do list and focusing on urgent or time sensitive tasks instead of doing everything- this involves learning how to prioritise things. 
  • Organising  schedules to give themselves time to  relax, and pursue their own interests.
  • Sharing feelings and burdens with family, friends, as well as professionals to help vent as well as gain solutions. 
  • Another thing that a person can do to manage stress is to acknowledge the signs of anxiety and depression, or lack of motivation. It is important to be mindful of any changes.
  • Taking a step back and reviewing their working conditions and demands in their workplace with their supervisor and finding ways to reduce the load of their work.

Conclusion

In this article we have answered the question “How do smartwatches measure stress?”

We also briefly discussed whether smartwatches can accurately measure stress, what stress is, how it impacts one’s life, and what one can do to manage stress. 

FAQ related to how do smartwatches measure stress?

Can smartwatches detect stress?

Yes, smart watches can detect stress. Smart watches measure stress level by measuring the length of time between heartbeats, this measurement is called Heart Rate Variability. 

Do smartwatches cause anxiety?

Yes, according to research by the National Institutes of Health-funded smart watches can affect users’ peace of mind and cause anxiety. 

Do smartwatches help with anxiety?

No. Smartwatches are believed to be linked to higher levels of anxiety according to research due to heightened awareness and attention to normal and abnormal fluctuations in heart rates, which could lead to health anxiety. 

How much stress is normal in smartwatch?

References

Felman.A. Why stress happens and how to manage it. MedicalNewsToday. Retired on 15th April 2022. https://www.medicalnewstoday.com/articles/145855

Michael Sawh. Stress wearables: best devices that monitor stress and how they work. Wearable. Retrieved on 15th April 2022. https://www.wareable.com/health-and-wellbeing/stress-monitoring-wearables-explained-7969

Himanshu Kansal. How Does Stress Monitor Work In A Smartwatch? Is It Reliable? Wearables to use. Retrieved on 15th April 2022. https://wearablestouse.com/blog/2021/12/29/how-stress-monitor-works-smartwatch/#:~:text=These%20days%2C%20 most%20 smartwatches%20use,pressure%2C%20breathing%2C%20and%20digestion.

What Is the Stress Level Feature on My Garmin Watch? Garmin. Retired on 15th April 2022.https://support.garmin.com/en-US/?faq=WT9BmhjacO4ZpxbCc0EKn9

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