<15% REM sleep increases HR significantly

[mccoy]

19 hours ago, Mike41 said:

...my sleep is so fragmented. 4-5 awakening a night

I estimate about 10-20 awakenings a night for me, but they are pretty short, I fall asleep usually very soon.

I have a personal theory for sleep fragmentation which is an inference from the data published by Matthew Walker in his book.

Sleep fragmentation can be a distinct advantage in a hostile environment for obvious reasons. So, it may be that it is an evolutionary feature of human communities. A group of humans has some deep sleepers and some fragmented sleepers. At night, fragmented sleepers have a higher likelihood to perceive threat situations. At day the deep sleepers have more energy and stamina, they are the main warriors and lead the hunting expeditions. But both are necessary. So sleep fragmentation may just be a genetic feature and we may not be able to do much about it. Fragmented sleepers probably have long stretches of REM sleep. I think I do, since I dream a lot. 

But having a device which can measure that with some accuracy is far better than estimation or speculation.

 

18 hours ago, Thomas G said:

n general I get plenty of REM sleep (on the nights when I sleep long enough), and I am a bit troubled by how little deep sleep I get. I'm not sure much can be done about that for now. I also wish I understood the science better on that front because I have a lot of questions based on the reading I've done.

My suspicion is that I too have abundant REM sleep and too little NREM. Have you tried going to bed earlier and eat less at night?

[Ron Put]

On 7/26/2020 at 5:41 PM, Thomas G said:

For the most part I don't mind the headset, and I do wear it and sleep fine. I don't have a fitbit so I can't compare it to that, but it is much more accurate than the dumb cheap apps I was trying on my phone.

Even if I was convinced (which I am not) that this thing was highly accurate, the headband bit would bother me, I think.   But seeing that it confuses light sleep with watching TV suggests to me that it relies to a large extent on movement too.  BTW, Fitbit doesn't only rely on movement, but also on heart rate:

"Fitbit estimates your sleep stages using a combination of your movement and heart-rate patterns. When you haven’t moved for about an hour, your tracker or watch assumes that you’re asleep. Additional data—such as the length of time your movements are indicative of sleep behavior (such as rolling over, etc.)—help confirm that you’re asleep. While you’re sleeping, your device tracks the beat-to-beat changes in your heart rate, known as heart rate variability (HRV), which fluctuate as you transition between light sleep, deep sleep, and REM sleep stages."

As to accuracy, it appears to undercount REM by about 35% and deep sleep by 50%, while overcounting light sleep, according to this:

Tracking sleep: Does Fitbit measure up to clinical standards?

I personally am happy with Fitbit for sleep tracking, and it has noticeably improved over the time I've had it. From what I've seen, it's among the currently most accurate wearables for sleep tracking, although I might switch to Garmin eventually because it's a bit better for higher intensity HR tracking, plus I don't like the subscription model being pushed by Fitbit

I should qualify "happy" as I mean that I use the data similarly to how I use the body fat and muscle mass data from my Withings scale -- as providing a baseline and tracking longer-term changes.  Broadly speaking, Fitbit's sleep score corresponds to how I feel during the day, just like broadly speaking, the Withings scale corresponded to what I saw on a DEXA scan and I'll verify if the changes in body composition I see on the scale correspond to the scan I'll get sometime later this year.

[Thomas G]

9 hours ago, Ron Put said:

But seeing that it confuses light sleep with watching TV

I'm not sure where you are getting this. I use DREEM almost every night and it has never once made this error.

[Ron Put]

11 hours ago, Thomas G said:

I'm not sure where you are getting this. I use DREEM almost every night and it has never once made this error.

It was one of the complaints I saw in the user comments.  It's possible that the algorithm has improved since, as the Fitbit Versa used to do it occasionally when I first got it and it doesn't anymore.

[mccoy]

3 hours ago, Ron Put said:

It was one of the complaints I saw in the user comments.

Maybe the user really fell asleep while thinking he was still watching TV!!!