How does my watch know that I am stress ?

It uses technology licensed from Firstbeat which can determine physical body stress from the changes in the variability of your heart rate.
This can sometimes be used as a proxy for emotional stress as well but it meant primarily as a sign of bodily stress - an overworked body from too much training, or a body that is fighting the first signs of an illness are two examples.

Hopefully the guy from Firstbeat who is active on these forums will come along and give a more in-depth explanation, but I believe in a nutshell that is how it works.

Very, very well nutshellized Carl. Couldn't have said it better myself.

Paulyeo, yes, that's the gist of it.

If you're curious about the science, here's a really nice break down from a colleague of mine. She's specifically talking about the Firstbeat Lifestyle Assessment, which is a service we do with healthcare professionals and corporate wellness programs, but the science is essentially the same - in terms of what's being looked at and why it works.

https://www.firstbeat.com/en/news/beyond-heart-rate-heart-rate-variability/

HermanB: How precise and realible this all stress monitoring is? A was wearing two differenct devices (VivoSmart 3 and Fenix 5) on the same hand for a couple of days, and the results werent very convincing ... One device was reporting, I had enough rest, the other was reporting I should rest more ... All other circumstances the same, of course. I would really appreciate to get some help with this, I find it extremely useful functions, but it seems quite premature to me yet.

Well, the science is well-established.

To be honest, I'm never entirely sure how to answer most "reliable" or "precise" questions, because accuracy is - in a practical real-world sense - is always tied to use. For example, I have an antique clock in my kitchen that I need to wind up once a week with a key. It's certainly not accurate in the sense that an NIST atomic clock is accurate, and yet... I'm never late for work. It is perfectly accurate for my needs, although, I won't be winding it up and shipping it off to NASA in hopes that they use it to countdown to ignition.

If the question is whether the stress feedback is reliable and precise enough to give you a little better insight into your body and how you are impacted by the demands of life and environment, or even looking at something like whether your sleep is restorative (quality) instead of just long (quantity), then for most folks it seems to be working just fine.

For what it's worth, there are a number of well documented problems related to wearing multiple wearables on the same hand. I can confirm this from personal experience. In addition to at least one, or both, devices being outside their "ideal" wearing position - they can also knock into each other and shift around. But don't just take my word for it.

[QUOTE=DC Rainmaker]The bigger issue here is them wearing two optical HR sensor devices per wrist (which they did on all participants). Doing so affects other optical HR sensors on that wrist. This is very well known and easily demonstrated, especially if one of the watches/bands is worn tightly. In fact, every single optical HR sensor company out there knows this, and is a key reason why none of them do dual-wrist testing anymore. It’s also why I stopped doing any dual wrist testing about 3 years ago for watches. One watch, one wrist. Period.

If you want a fun ‘try at home’ experiment, go ahead and put on one watch with an optical HR sensor. Now pick a nice steady-state activity (ideally a treadmill, perhaps a stationary bike), and then put another watch on that same wrist and place it nice and snug (as you would with an optical HR sensor). You’ll likely start to see fluctuations in accuracy. Especially with a sample size of 60 people (or 120 wrists).


https://www.dcrainmaker.com/2017/06/thoughts-on-the-wearables-studies-including-the-stanford-wearables-study.html

Hi All

thsnk you you very got all of you sharing on my post.
I was very stress during last 2 week . Because I am travel to many country and lack of sleep.

Now I go back and check it my watch stress report it does able to detect correctly ? Because to day I am sick. I can see my stress level keep go up trend

HermanB: Your point taken, thank you for reply. Your perception of "reliable" or "precise" is just fine for me. But I am afraid, we are not even there ...

So, I decided to do new test, and bought a new Fenix 5S for that (firmware 6.00). This Fenix 5S on the left hand, VivoSmart 3 on the right hand. See attached picture.

I will have better results within couple days, but already these first hours show, that it is the same situation, as when both devices were on one hand - i.e. Fenix 5S doesnt pick some higher stress situations (or the VivoSmart is exaggerating stress, which, in my opinion, is not the case here). To describe the situation on the pictures: from 12 a.m. to 3:30 a.m. I was driving a car, then I went to bed. Sleep data are manually adjusted, but more or less correctly picked by both devices.

So, what do I see on the pictures: Fenix 5S thinks that when I drive a car, I am less stressed, the when I sleep. How should I understand this?

However, I have to decide, whether to keep the Fenix 5S, or to get rid of it. I dont find its stress data very meaningful, therefore having doubts about other data too.

Thanks for any tips. ciq.forums.garmin.com/.../1274204.gif

Where do I get this information on the Stress on the Fenix 5? Thanks.

So, what do I see on the pictures: Fenix 5S thinks that when I drive a car, I am less stressed, the when I sleep. How should I understand this?

However, I have to decide, whether to keep the Fenix 5S, or to get rid of it. I dont find its stress data very meaningful, therefore having doubts about other data too.

Thanks for any tips.

Hi Selma - looking at those two pictures it does look like something is 'off' but figuring out what exactly isn't easy.

I asked around to see if anyone had any good suggestions.

One expert guess was that somehow your different devices have managed to detect different minimum heart rates... and that is throwing the scaling of the data out of whack. Providing that there isn't some sort of hardware/sensor problem, then it should "fix itself" over time with regular wear. This may mean wearing it overnight, for good resting data.

Not sure if that's it, but hope it helps.

Where do I get this information on the Stress on the Fenix 5? Thanks.

Provided you are on the latest firmwear, you just need to select and add the stress widget. That's it. ;-)

Hi All

i just notice that my Garmin fenix 5 can show me I am high stree for 3% in one day.

may I know it is accurate ?

I'm sure you're not married

Hi guys, I too have issues with the stress recording. Can anybody who knows how this works tell me their thoughts on last nights report. I went to bed at 2300 and work just after 0600. No restful moments at all according to my watch. ciq.forums.garmin.com/.../1307838.png