On: Custom firmware for MI fitness band

[FirmwareBurner]

But what does that tell you about your sleep cycles and sleep quality? It just shows you moving around in bed.

[cj → FirmwareBurner]

Isn't "movement in bed" how all sleep monitors work? (aside from the clinical test with electrodes stuck to your head)

I always assumed the main metric used by sleep apps for watches is movement.

[FirmwareBurner → cj]

>Isn't "movement in bed" how all sleep monitors work?

No.

The best ones monitor your brainwaves, and the best wearables monitor the next best ting, your hear rate and blood oxygen.

You can get knocked out by drugs, alcohol or just die in your sleep from apnea so you'll not move around in bed and your bed motion sensors are useless.

You need to tap into the body's vital signs to know your sleep stages accurately, especially REM.

[cj → FirmwareBurner]

For anyone interested in how Apple Watch measures sleep stages, here's a deep dive that goes into details about how the accelerator is used to estimate respiration rate, etc in order to classify sleep stages

https://www.apple.com/healthcare/docs/site/Estimating_Sleep_...

[dariosalvi78 → FirmwareBurner]

Sleep cycles are very hard to measure reliably, basically no wrist worn device should be trusted for that.

[cj → dariosalvi78]

I find wrist sleep apps accurate enough for showing me trends over time and correlations between things that make sleep worse (e.g. drinking before bed shows different sleeping patterns than not drinking). Interesting and useful data but I agree it's not scientifically precise.

[dariosalvi78 → cj]

I agree, which is why I think that it would be more interesting, and probably more honest, to show some sort of "sleep quality" index instead.