Samsung Galaxy Watch 4: An Accurate SLEEP Tracker?

🔴 Affiliate* link: https://geni.us/GalaxyWatch4
🟢 Instagram:   / quantified_scientist  
🔵 Newsletter: www.robterhorst.com
🟡 Twitter: @QuantifiedRob
* Affiliate (paid) links support the channel by earning me a small commission on any sale, and it doesn't cost you any more! My opinions are completely my own, and this content is not sponsored.
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
👇 $30 off any new WHOOP membership, affiliate* (paid) link, supports the channel!👇
join.whoop.com/QuantifiedScientist ($30 off any new WHOOP membership)
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
👇Amazon Affiliate* (paid) links. Supports the channel, doesn't cost you any more!👇
Huawei Watch GT 3: https://geni.us/Huawei_Watch_GT3
Apple Watch 41 mm: https://geni.us/AppleWatch7_41
Apple Watch 45 mm: https://geni.us/AppleWatch7
Garmin Vivomove Sport: https://geni.us/GarminVivomoveSport
Garmin Epix 2: https://geni.us/Garmin_Epix_2
Garmin Fenix 7: https://geni.us/Garmin_Fenix_7
Garmin Venu 2 Plus: https://geni.us/GarminVenu2Plus
Garmin Venu 2: https://geni.us/Garmin_Venu_2
Garmin Venu 2S: https://geni.us/Garmin_Venu_2S
Garmin Venu 2 Plus: https://geni.us/GarminVenu2Plus
Fitbit Charge 5: https://geni.us/FitbitCharge5
Fitbit Luxe: https://geni.us/Fitbit_Luxe
Fitbit Charge 4: https://geni.us/wjAfjU
Fitbit Sense: https://geni.us/CSfYQE8
Fitbit Inspire 2: https://geni.us/iZHlb
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬
📸My Gear* (paid links, supports the channel and doesn’t cost you any more)📸
Camera body (main): https://geni.us/SonyA6600_body
Camera lense (main): https://geni.us/sony_sel_18-135
Camera (B-roll): https://geni.us/CanonEosM50MarkII
Light: https://geni.us/Godox_VL150
Softbox: https://geni.us/NiceFotoSoftbox
Light stand: https://geni.us/WalimexLightstand
▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬▬

Intro:
If you wear two Galaxy Watch 4’s at the same time, will they measure the same sleep stages? You would at least hope so, but you might be surprised by some of the findings in this video. If the two watches are not consistent, that means that either the raw measurements themselves or the algorithm underneath is not very stable. That is what I will check in this video for the sleep tracking of the Galaxy Watch 4. For 6 nights, I wore one Galaxy Watch 4 on my left arm and one on my right arm, both running the same firmware. I also wore this EEG headband that can actually measure my brainwaves, which provides relatively reliable sleep tracking. Now, the fact that I wore one watch on the left and one on the right hand could introduce some differences in the movement data both watches record during sleep. However, again, this is something that the algorithm should be able to deal with. If not, this means it is inherently unreliable at estimating your sleep stages. Let’s see if this is the case!

Conclusions:
Based on these preliminary results, I do not expect the actual sleep tracking to have changed with the new firmware, or I at least do not expect it to have improved. Now, I just tested it two nights, and also one one of the watches was not the “classic” version of the watch, which has the same sensors and software, but a slightly different design and weight. So, further testing is needed to make 100% sure nothing has changed, but as I said, I do not see any evidence of significant improvements.
Overall the sleep tracking of the Galaxy Watch 4 is mediocre at best. The most telling for me is the fact that two watches worn at the same time give such different results. I think that as it stands, the main relatively reliable use-case of the sleep tracking functionality of the Galaxy Watch 4 is tracking your total time spent in bed. However, I wouldn’t really trust the tracking of the individual sleep stages. If that is important to you, Whoop, Fitbit and the Withings Sleep analyzer are better options. I’ll be testing many more devices, and I am also working on ranking the different wearables I’ve tested so far in terms of accuracy for heart rate and sleep. If you would like to see those videos and more, consider subscribing. I also did a complete review of the Galaxy Watch 4, which is linked up here. It also helps the channel, and of course makes me feel happy, if you like this video and leave a comment, but that is of course totally up to you! See you in the next video and have a great day!

Timestamps:
00:00 Short Intro
00:47 Sleep Stages
04:37 Sleep Start/End
05:43 EEG Test
08:54 Other Devices
09:30 Software Update
12:49 Recommendations