Stress at night higher than during day time

I don't usually do hard core chilling for hours at daytime, so the night is always the lowest stress period for me. If I have lots of work related things on my mind and busy days, I usually don't sleep as well as normal. Then my stress level during the night can be over 20. And during very relaxed times in a weekend, the stress level can be under 10 in the night. I often see stress fluctuations that follow the sleep cycles with 1.5 hour intervals during the night. 

I think the mind can be working hard and have higher stress level than normal even during sleep. The watch will pick that up. But readings are individual from person to person, and you need to figure out what is a normal/good/bad reading just for you. 

ovekvam said:

I often see stress fluctuations that follow the sleep cycles with 1.5 hour intervals during the night. 

Thanks a lot for the response, very helpful as always.

The above was indeed my first thought so I had a look at if I could establish correlations between stress factor at night and the other data provided by the watch, including sleep stages. But in my case I couldn't find any obvious correlation, with the exception of one very obvious: between stress and the level of saturation of the oxymeter (stress increases when O2 saturation decreases, which makes sense to me).

My understanding is that REM sleep generates meaningful levels of brainwave activity so to me it would seem reasonable that during this particular stage, stress goes up. But I couldn't correlate these 2 datas. With that said, I'm not sold on the accuracy of the sleep stages advertised by Garmin and it could very well be that stress correlates with actual REM stages.

Below is an example of what I call an unsatisfactory night from a stress perspective overall. Was last night.

JRKingOfBeer said:

REM sleep generates meaningful levels of brainwave activity so to me it would seem reasonable that during this particular stage, stress goes up

You should understand that the stress measured by the clock is cardiovascular stress, not brain activity stress. These concepts are easy to confuse, but in general they are different things. What the watch shows is all derived from heart rate variability and acceleration data from the hand. To put it bluntly, they are not particularly accurate. Therefore, I would not be so careful about the boundaries of the stress level in the pictures.

global_local said:

the stress measured by the clock is cardiovascular stress, not brain activity stress

Yes I understand this. I am willing to believe that a higher level of mental activity will generate cardiovascular stress and as far as I'm concerned, this seems to be the feedback I'm getting from my device. For example, as I said earlier I sit at my desk watching youtube, my HRV on a Sunday has the potential to become real low, as I said I've seen zero before. But, if I start writing an email requiring me to focus on what to say etc... my stress will shoot up (50 easily). In my - again personnal, case, I can't say for others - both are fairly correlated from what I can observe.

Your point is acknowledged, these are not the same thing. And I also agree with you that the charts have to be interpreted with having loose boundaries. I am looking at those with this in mind.

There seems to be a correlation between mental stress and indicated stress level on the watch both during daytime and during sleep, at least in my case. The indicated stress level also correlates quite well with how I felt about the sleep quality. It is also indicated on the sleep score. Higher stress lowers the score.

ovekvam said:

The indicated stress level also correlates quite well with how I felt about the sleep quality

I agree with you, and - at least for me - the difference in stress between a night I felt "good" and a "so so" one, isn't large in absolute number. It's the difference between a 15, and a 20. BUT, this seemingly small difference in number matters a lot in how I feel in my case. This is precisely the reason why I'm keen to try to lower it from 20 to a lower number as much as I can.

What I am thinking, is that this could also explain why the "Good" stress factor band is fairly narrow. I'm not sure what it is exactly but I do now that a 16 is "Fair", a 15 is "Good", and a 10 is "Excellent". So, the "Good" band is at the most 5 points wide: this is not a lot.

I can't say why your night time stress is higher than daytime stress. However I can say that if you want to keep your night time stress to a minimum, try to do some breathing excercises right before falling asleep.
My usual stress score for the night is around 15-20. If I do the breathing exercises from the watch (I think the english name for the particular one is "coherence"), that drops to 12-15. I can get even lower (9-12) if I do a 20 minute resonance breating session, as described in "Hearth Breath Mind" by Leah Lagos

I find similar trends to what you're describing and frankly I have no Idea what's going on there (no alcohol, good sleep hygeine, often take magnesium supplements). I do train a lot, but actually my overnight stress is lowest after a long workout day (parasympathetic hrv bias I guess).

Normally though, I see quite low stress during the day and then my stress almost plateaus at 20-25 overnight. This is always most dramatic after a rest day (without training), so there is definitely something strange going on.

I'm not actually worried about the sensor accuracy itself, HR and HRV on recent sensors align really well with most other wearable tech, especially at rest. But I'm definitely curious about a) what is going on in my body and b) how garmin's algorithms are interpreting this.

One possibility, though uncommon, might be parasympathetic saturation, basically HRV is surpressed when lying in a horizontal position. This occasionally occurs in athletes with a high training load, but it seems quite rare and I'm not really sure how one would test this. I do find my morning snapshot HRV (sitting) is always much higher than my overnight HRV.