How Much Sleep Do Fitbit Users Really Get?
blog.fitbit.com
blog.fitbit.com
It frequently counts me as sleeping when I sit down to watch TV in the evening, or read a book in bed. Sometimes I stay up until 1am reading and it always tracks me as deep sleep from 10pm when I got into bed. I usually take it off for my morning shower (It is waterproof, it just annoys me when washing) and it nearly always counts the walking from bed to shower as a few minutes of restless sleep and the shower itself as deep sleep.
I'm not sure how it makes an assesment of my sleep level. I don't know if it's just based on movement or if it takes heart rate data into account but it does have a heart rate sensor. It seems to usually be wrong.
In theroy it would be possible to know about these limitations and adjust your use of it to make it more accurate, but unless the participents of the study are aware of that and have been manually correcting the data then that won't be the case.
(Not a general critisim on the device, I like it for everything else, but it's sleep data is clearly rather inaccurate)
However it marks me as awake during that sleep time, so I guess it's accurate?
Fitbits have 2 measurement modes for sleep - normal and sensitive. Normal pretty much tracks me as sleeping like the dead for 8 hours each night (however long I'm immobile in bed). Sensitive, on the other hand, tracks much more detail and can tell when I'm restless, sleeping deeply, and even when I get up in the night and move around. I highly recommend the sensitive sleep setting for Fitbit users - it gives you more data to play with!
Fitbit recently re-worked the way they track sleep in its HR-monitor-equipped devices (Charge 2, Aria HR, etc.). It introduced more details (it was just tracking restless/deep before) and this upgrade greatly improved the sleep tracking for me. Before Sleep Stages, it would track only 3-4 hours of my sleep each night. Now, it catches the full 6-9 hours.
Now, all of this is to be taken with a grain of salt in terms of accuracy, but to compare among Fitbit users and to yourself over time, this information is incredibly useful!
The strongest example of the usefulness of this for me so far has been the effect of moderate alcohol consumption on the quality of my sleep. I am far more restless and get much poorer sleep after drinking just 1-2 beers on a full stomach. This has led me to cut back almost completely on alcohol and the quality of my rest has dramatically improved!
From what I can tell, none of these accelerometer-based methods work at all and the companies pushing these as sleep trackers are making false claims.
Setting the sensitivity to "normal" just raises the noise floor in their filter so high that it obscures the data.On sensitive, I've never had issues with it identifying "sitting" as "sleeping", yet it still effectively tracks my sleep (including periods of wakefulness immediately pre- and post- slumber in bed as well as mid-night disruptions that wake me up). This suggests that I'm getting pretty good data (though not equivalent to a sleep study with ECG/EKG equipment). In this case, "good" is good enough for my uses.
I'm curious, did you not notice this before? I have an MS Band, but the sleep tracking seems similar to the new Fitbit tracking. It did give me some concrete data on how drinking affects my sleep, but that data wasn't really valuable because I already knew that drinking too much or too late would have a negative impact on my sleep because I felt tired the next morning.
Having months of daily Fitbit records that I could look back on well after I forgot about my "rough morning" the following day drove the point home as only hard data could.
Speaking as a Fitbit Charge 2 user, none of that happens with my device. I don't know how accurate the rest of the data is, but it does track sleep only when I'm actually sleeping.
It would accurately identify when I was asleep vs just sitting still, and lest you think it was biased towards nights, it accurately counted naps on the rare occasions I took one. The only thing it was BAD at was managing the data when changing timezones. I can hardly blame it. Who really knows what "time" it was when I was half-sleeping on the plane to Australia, and the clock is wrong anyway until I sync it two days later.
This is why I pushed for sleep on v1 of Microsoft Band to be manually triggered. Eventually cloud detected sleep was lit up, but we benefited from lots of gathered data at that point, but even so, it is a hard problem to solve. The best solution would be per user training, allowing users to correct auto detection and use that to improve future tracking, but AFAIK no one in industry is doing that.
> I'm not sure how it makes an assesment of my sleep level. I don't know if it's just based on movement or if it takes heart rate data into account
This is an incredibly hard problem. For sleep studies, multiple doctors look over all the vitals gathered (and for a full sleep clinic study, subjects are very wired up!) And to determine when the subject is in a given phase of sleep, they vote, and it is not always a consensus decision![0] Trying to then make a machine algorithm out of that is difficult, especially working with consumer level sensors.
That said, across most users, data tend to be mostly correct, which is what these consumer devices target. Being able to say someone got 7.5hrs of sleep is good enough, the 10 minute bathroom break doesn't impact the overall numbers too much. Being able to give a good summary of weeks and months is huge, and being able to spot large regressions and improvements is key to user satisfaction.
The ultimate goal is to gather a lot of data, noise or not, run it through machine learning, and start being able to give people actionable advice that they will see real results from.
[0] this was relayed to me by the team who doing sleep classification, other sleep studies may happen differently.
They conclude that sleep trackers are good for creating awareness of your sleepquota.
[1] https://www.heise.de/ct/ausgabe/2015-25-Schlaftracker-vs-Sch...
The 935 also has "Move IQ" events where it auto-detects certain patterns. It captures when I walk my dog, and even captured some laps I did in the pool the other day. The optical heart rate tracking also looks pretty good.
https://help.fitbit.com/articles/en_US/Help_article/2163#Aut...
Other than that it's pretty accurate, it even detects the occasional 15 steps to the toilet and back as awake time and I'm generally happy with it.
It has a heart rate sensor but AFAIK you need to put some other firmware on it to use that during the night at predefined intervals.
Regarding tracking sleep quality (it only has light, deep and no sleep as categories), I feel it tracks it well enough and I treat the duration of deep sleep as an upper bound (usually around 2h30).
So if the band shows me little deep sleep it's almost always correct (i.e. I don't feel I slept well). If it shows lots of deep sleep I can sometime confirm and sometimes not.
Of course, all this is subjective, so "sample size = 1" holds ;)
Fitbit rolled out their new sleep types tracking and I find out I'm actually a super light sleeper. Most nights I don't get anywhere near the low-end benchmark for Deep Sleep and I overshoot the high-end benchmark for Light Sleep by many points.
It's weird because my subjective experience and the data that Fitbit shows are so out of whack. I could swear that I sleep well, but nope.
Who's really right here then? I'm curious, if you have some nights where the Fitbit says you sleep better or worse than average, does that correlate with your subjective experience?
All the stages have some benefit. https://help.fitbit.com/articles/en_US/Help_article/2163#Dif...
I'm with you though. I thought I was doing a good job on sleep and then picked up a Charge 2 and was super surprised at just how little I was getting. It's helped me get better at going to bed at a reasonable hour.
I don't sleep much, I never have. However, I can pretty much shut my body down and meditate, which probably has similar outward physiological expressions as sleep.
I call it my time in my rejuvenation center. It isn't sleep. I'll do that for hours and then get three to five hours of sleep - estimating, of course.
When I did my sleep study, they asked me to not do that. So, I sat there awake and it was not a very fruitful study. I am sure I am not unique but I am only finding generic information when I search.
I stay nearly perfectly still, inasmuch as a human can, and meditate. Once I am asleep, I guess I toss and turn, as well as snore. I highly doubt that I am unique, in these regards.
The proscribed medical solution is a rotation of pharmacutical sleep aids. I don't usually bother with them, as I dislike the groggy feeling that I have the following day.
But yeah, I am very much awake. My pulse rate slows, as does my respiration. At some point, I'll change position and that's when I have actually fallen asleep. The duration varies, and I sometimes just give up and go do something else.
Right now, I don't have much control over ambient light, but I'd like to find a solution. I think that probably means automatically opening window shades in the summer (anyone tried this?) and, since I live in Seattle, a 10 KW spotlight rigged to a timer in the winter...
Everyone who owns a fitbit has doubtless signed off on being part of these kinds of studies if you dig all the way into fitbits EULA, but I bet none of them actually got an email saying "click here to opt in/out". For a lot of fitbit users, they will never see this study and it will never cross their mind that they're being studied.
This is why I searched high and low for a fitness tracker that doesn't have an online component. I eventually settled on a garman fitness watch plugged into turtle sport: http://turtlesport.sourceforge.net/EN/home.html
What am I supposed to take away from this?
I guess, the inner clock is adjusted to that time because that's when the sun goes down in summer, and when melanin increases, because of changing light levels, we become sleepy.
just , a shot in the dark so to speak ;)
We don't actually know where those stats come from, so this conclusion is a bit far-fetched: "these findings further support the general recommendation that most adults need to consistently sleep 7 to 9 hours per night".
The movement data is probably enough to tell when I've slept better or worse, but I wouldn't trust the absolute "number of hours of sleep" they report.
But doctors don't seem to trust the consumer devices (probably with good reason). When I had an actigraphy, they used a special device made by Phillips, and used the results to verify that the sleep study results weren't a one-off night.
My work has been traditionally done with AASM sleep labels which may be a bit more complex that what fitbit uses, so that may bring up their overall accuracy. Additionally I assume that fitbit would use a hidden markov model to predict the sleep stages (which can produce very deceptive results in the context of sleep IMO). I'd say that this would bring their overall accuracy up to around 55% based upon my best guess.
Sounds like you are getting better sleep than most healthy people. I always wondered if one could benefit from a CPAP machine even without suffering from sleep apnea.
You are right, I should be grateful for the machine. But the mask is a hassle and I find myself getting cranky about it. Still, I wear it every night. It was definitely reassuring to see what a difference it makes.
I should try and talk my partner into trying it. ;-)
Other interesting notes:
1. Women need an extra half hour?
2. People sleep less as they age?
3. "Generation Z" is what we're calling kids these days?
In my experience a lot of older people seem to say this. Note sure why it's true.
"The mean sleep duration (from PAM) equaled 7.29±0.8 (S.D.) hr compared to 7.84±0.62 hr as estimated from the daily diaries. Neither parameter was correlated significantly with age (p>0.05)"
(N=43, 9 days, age range 21-83)
Because after age 30 your body, more or less, starts to die. There is a lot of discomfort and pain that is usually associated with this and as a result affects the quality and duration of sleep.
Could be differences in daily stress and work life that interferes with sleep and the ability to fall asleep.
Though, I don't think I'm using their new sleep phase metrics, as my Fitbit app doesn't seem to have it.
In a way, finding you have sleep apnea is good news because getting successfully treated is a TREMENDOUS improvement to your quality of life.
The only thing I know I have is some form of restless leg syndrome. Often I go to sleep without symptoms that I can feel (thank god, it's terrible), but apparently I kick a lot in my sleep like a dog.
I'd like that explained to me. If it's something that happens near the beginning of the night how does duration affect it?
Disclosure: volunteer beta tester
If this data is accurate, it could be useful in determining a country's future economics. Ie. perhaps a general population's 5 mins of average less sleep means more stress which means more economic downturn/changes?
The results I've gotten from the SleepCycle iPhone app - all the way back in 2009 - are more precise than any of those other fitness trackers. It used to rely on the uber-sensitive iPhone accelerometer but they "recently" switched to using the microphone for some reason.
But...it was designed and implemented by embedded engineers who looked at TIFF and thought it wasn't batshit enough.
http://garmin.kiesewetter.nl/ is useful for converting them to CSV and extracting the data that way.
That will do it for you.
I understand being skeptical of the accelerometer + hr monitor solution, there are certainly more involved ways of analyzing patterns that are available to sleep specialists. But how does it help the discussion to dismiss it in favor of a non-existent product?
I'm sure it's not accurate down to the minute, but I do think it gives me a general idea of how much sleep I get. For me, that's fine, and really all I need.
... come to think of it.....
https://community.fitbit.com/t5/Feature-Suggestions/Sleep-St...