Quantified Self Experiments / QS - apps and devices i'm using #2


I’ve already described which apps and wearables I was using but last few months my QS stack were updated. But let me explain logic I’m using to choose a good tracking device.

Collecting data is not free and we pay in terms of:

But thats not as easy as it may look:

And a few cautions:


Sleep is #1 priority for health and longevity and might be most serious tracking in my QS stack. I’ve used several non-EEG wearables and all of them were not accurate enough to measure effect sizes of interest. I’m healthy and have ~90 minutes of N3 per night and the effect sizes for most powerful interventions do not exceed 20-30 minute range. So error should be less than 10 minutes or so to see the effect of that power. This is 10/90=11% error and is already in a sleep specialist personal / ML approach error range. That means device should be almost in a gold standard range to have good chances to detect even strong effect.

Dreem 2 is my first EEG device, but company went bankrupt and I’ve switched to Hypnodyne ZMax which is more comfortable than Dreem 2 and provides raw data. Both devices are in a gold-standard accuracy range or just a bit lower.

But my current king of sleep is OpenBCI:

With this approach I assume that my data will be in gold-standard range for next 50+ years (Lindy effect) and its unlikely to become obsolete. That means i can make comparisons during period of my whole life and do not lose data continuity even when i change to another gold-standard device. I’ve travelled few times with this setup - so far so good.


Cardiovascular system seems to be the weakest point of human health leading to biggest cause of death on a planet right now. Heart rate during sleep can reveal sickness, nightly HRV seems to be even more sensitive to sickness and morning standing HRV can reveal ANS status and training adaptation. Daily HRV can be used to reveal stress levels.

Heart Rate

A lot of devices can track heart rate during sleep, but not all can track it during daytime or exercise:

I also sleep on Eight sleep but not using its metrics at all (data doesnt looks well compared to other devices).


HRV is harder to measure due to sensitivty to movements artifacts and arrithmia. PPG can measure it with acceptable accuracy only during stationary periods and even there it might be not accurate if one have frequent arrithmia.

Shimmer3 ECG is used to get gold-standard raw ECG data in 512Hz for 24/7 monitoring making my cardiovascular system tracking approach as solid as my sleep tracking.

Blood Pressure


Body and skin temperature can be used for sickness monitoring and to reveal circadian rhythm




I do meditate occasionally and tried different styles: NSDR, Mindfulness, Mantra, Dantian breathing. Now I’m building approach to analyse brain activity during meditation. I’ve used Muse 2 and Muse S for that but unsatisfied with signal qualtity.

Right now i’m switched to OpenBCI and have tried 16 channel setup with 1000Hz sampling rate:

It is hard to travel with Ultracortex, this is where i might use ZMax / Muse for convenience but do not expect good data.