# Monitoring devices I have loved

Every once in a while a measurement device improves my life a lot at little cost. This post is an attempt to share those data points and gather more, so we can all get a bunch of free gains.

The typical shape of problems solved by measurement devices is as follows: there's something I know might be an issue, but working on it feels very unrewarding. It's a combination of the costs of the issue being poorly quantified, not knowing how much any particular solution would help, and the solution requiring scarce resources like executive function. Measurement devices can help with any of these.

Note: I've provided links to the devices I use on the theory that something is better than nothing. I haven't necessarily tested competitors and there may be better options out there. Amazon links are affiliate, the others are not.

Devices that have helped me in particular
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**Air quality monitor.** I live in California, which has wildfires. Back in 2020 these were especially bad. I closed my windows and wasn't willing to buy more air filters, so I didn't see the point in getting a monitor. At a friend's urging I got one anyway. Turns out my indoor air quality was such that I was willing to buy more filters after all, but also closing the windows didn't help that much. Once I had the new filters I could open my windows enough to let the CO2 dissipate, a huge quality of life improvement.

Once I had the monitor it paid off in other ways. I'd always been vaguely aware stovetop cooking and anything in a spray can were bad for air quality, but I lacked the bandwidth to change my behavior. Once these actions reliably triggered little red lights on the monitor I started turning on the stove vent more, and wearing a mask to use cleaning products. Eventually this formed a habit such that I sometimes remember to do those things even without the air monitor's prompting.

As a bonus, the in-house monitor saved me from having to check air quality on PurpleAir every day, and meant I caught the odd bad day in the off-season. 

(This does depend on the monitor being accurate and having the right thresholds for greed/yellow/red. I chose [this one](https://amzn.to/3BIznZb) mostly for its feature set, but PM2.5 cut-offs do seem right ).

**Heart rate variability monitor:** Heart rate variability, the delta in the space between your average heartbeat duration, is a pretty good and extremely responsive measure of stress (up to a point higher is better because it indicates more PSNS activity). Via the [Lief](https://getlief.com/) I learned that nothing I do matters for HRV except breathing, and was able to focus my stress reduction efforts on that, and this indeed left me feeling less stressed than before.

Unfortunately, Lief is subscription only, and an expensive one at that. I only wanted to monitor my heart rate variability occasionally, so it wasn't worth the cost. When this next reaches the top of my list, I will look for a chest band I can own in exchange for money.

 Watchband and ring fitness trackers will sometimes claim to report HRV, but they're not very good. Measuring HRV requires very precise measurements, and the signal of the heartbeat gets fuzzier the further you are from the heart. When I look next I'll be looking for something favored by HIIT nerdjocks, because HIIT also requires very sensitive measurements.

**O2 Saturation Monitor.** [This](https://amzn.to/3BHG7X2) has saved me 2 or 3 trips to urgent care, when my breathing felt constrained but my oxygen levels were fine. I imagine it would be even more useful if it got me into the ER when I didn't know I needed it. 

More marginal tests
===================

**Nutrition testing**. Everyone is very happy to tell you your nutrition is bad and this will kill you. It's hard to know what matters most to you, or whether your solutions are working. After my [medical miracle](https://acesounderglass.com/), nutritional tests confirmed that a miracle did in fact occur, found which nutrients were still lagging, and helped me assess if particular treatments were working. These can be expensive, especially if you're testing for everything. They are probably unnecessary for most people, but if you're struggling nutritionally and especially if your attempts at treatments are having ambiguous results, numbers are helpful.   
  
Every doctor I've seen tells me urine tests are better than blood for most nutrients and prescribes [Metabolomix+](https://www.walkinlab.com/products/view/metabolomix-nutritional-test-fmv-urine-genova-test-kit).  This test is missing several important nutrients (most importantly iron and vitamin D, but also B5, choline, and vitamin K), although my doctors only seem concerned about iron and vitamin D.

**Home water testing**: these are periodic tests rather than continuous monitors, and aren't cheap either. My doctor recommended [this one](https://mytapscore.com/products/advanced-city-water-test) but it's more expensive than the [water filter](https://amzn.to/3PV8nvz) I use, so maybe find a cheaper one or skip straight to filtering (the test did verify my filter worked, and this was pretty late in the filter's lifecycle). You can also use [EWG](https://www.ewg.org/tapwater/) to check your city's water data, although it will miss problems in your own pipes.

Reports from other people
=========================

**Continuous glucose monitor.** People report both that seeing the immediate spike in blood sugar after dessert changes their behavior in ways willpower never could, and that the monitor lets them identify the things they love that don't cause spikes. This is on my list to try.

**CO2 Monitor**. I tried this but it turned out my sense of stuffiness tracks CO2 extremely well, so it's not that useful. The air quality meter I mentioned above has one built in and since it's there I do use it to trade off pollution and CO2, but I wouldn't miss it if it were gone. Other people like them though, and they can be useful in arguments with less CO2-sensitive people.

**FitBits et al:** Steps seem super motivating to some of you.

**Your suggestions here.** Please add more in the comments.