Amazfit puts out a lot of smart watches. Unlike, say, Apple or Samsung, they are willing to make design changes that extend beyond band width and bezel diameter. I like this. The Cheetah, which is not the Cheetah Pro, is absolutely targeted towards runners. I am a runner, but I would not be if given the choice. It’s just that if my heart is going to be pounding, sweat is going to be pouring, and the mind is incapable of a more complex thought than “bad place, get out now” I might as well run so I can live in denial about the cause.

It doesn’t seem to track anything more than the Amazfit GTS mini 4. As much as I am able to tell it tracks with accuracy no beer or worse than that cheaper device. It does offer some sort of subscription-required AI features for both sleep and exercise, called Zepp Aura and Zepp Coach respectively. Not having decided to take them up even on the offered free trial I can not comment on their utility. Anecdotally, Aura is some sort of large language model, with a strong guided-meditation flavor. It seems to require a linked phone or tablet, and this is probably because the Cheetah doesn’t have cellular or WiFi connectivity.

The display is big enough, that it doesn’t feel terrible when trying to read the compressed graphs of heart rate or sleep schedule. It also tracks stress, as a function of heart rate and breathing I think, which can be kind of upsetting. The ability to see your tracked data on a display that doesn’t feel cramped though, is a feature that really shouldn’t be overlooked.

At $200 USD from Amazon with their current discount, or $30 more directly from Amazfit I think that unless the Aura subscription is awesome, or one is really keen on the excersize features, it’s probably better to get one of their less expensive models. Otherwise you’re just paying for the larger display and longer battery life. It’s comfortable to wear, slim without feeling delicate, but I do kind of feel it’s not enough of an upgrade. Maybe I should have sprung for the Cheetah Pro, or one of the more advanced devices. I do know I like it enough to keep looking at the brand.

Sleepon produces a largish lozenge shaped device that unlike most of the products in the marketplace specifically and only tracks sleep. According to their ad copy it tracks: sleep stage, breathing rate, heart rate, body movement, snoring and et cetera. I expect the et cetera is a more professional way of indicating that whatever else can be extrapolated from the data gathered by the existing sensors is already or will be pending app updates. Those sensors are an accelerometer, blood oxygen concentration monitor, and a heart rate monitor. If that doesn’t seem like terribly much, one should keep in mind that any one sensor can provide multiple tracked values either alone or in conjunction with another sensor. A heart rate sensor will not only allow for recording of current heart rate, but heart rate over time and therefore heart rate variability. It all comes down to what can be done with data in the app. First, about the device itself. It’s something that fits into a silicone ring style holder to be worn on a finger overnight. The holder is open on two sides, one opening is for the sensor compliment which faces the inside of the finger. The other opening is opposite, and exists for the proprietary two contact charging base. The charging base is rubberized on the bottom, and has a noticeable weight, which is nice, but a micro USB female input which is not nice. Officially the ring has a two night battery life, you may get three, but in practice a habit should then be formed where the ring lives on the base and is put on the finger just before sleep, and is returned to the base upon waking. That’s a further important point. It’s constantly sampling, and is not intended to be worn except while sleeping. In my particular situation this is inconvenient because I have a tendency to lay down and sleep whenever and wherever I think I might be able to. There’s no assurance that it’ll be beside the right nightstand. Of course wearing the device is important because the bigger the dataset the more potentially useful it is and the greater the chance that once can track improvement over time. What might be improved? Quite a bit, and to get an idea of what bits exactly it will be necessary to see what the app tracks. Blood oxygen level, resting heart rate, heart rate variability, time asleep and time awake, sleep stages (light, deep, REM, or awake), the time spent in each, and finally though perhaps most interestingly apneas and hypopneas. Impaired or obstructed breathing during sleep can do worse things than inflict snoring on anyone laying beside. Low oxygen levels during sleep are a significant contributor to morning tiredness, or headache. The app will recommend some immediate actions such as avoiding sleeping on ones back, but it will also suggest weight loss and exercises to improve fitness and lung function. That’s where having a lot of history comes in handy. Along those same lines the app offers a thoughtful export feature for everyone who’s not averse to a little data mining. The app itself takes the time period approach and provides daily, weekly, and monthly top level tabs in addition to an aggregate sleep score out of one hundred. There’s the option to create labels to assign to ones sleep and the ability to maintain a sleep diary in the app. Those are both features which only allow for getting out of them what’s put into them. Next comes sleep time and sleep stage. For each of these it’s going to give you a formal rank of the Goldilocks variety. A value called AHI is presented, where the acronym is for apnea hypopnea index. I expect very few people will be aware of or comfortable with that measurement initially, over time it should become familiar and useful. Heart rate and heart rate variability follow, along with blood oxygen, and a log of movement during sleep. The movement can be sort of obscure on its own, but viewed against the sleep stage graph it proves more interesting. I’ve found that it, at times when I wake but the tracker does not register myself as having awoken, may just register significantly increased movement instead. The tracking of ones sleep deficit is interesting as well. It’s one of those things that people are aware of, and likely do not keep track of in any concrete way. It may be slightly too easy to let it turn from a novel metric into a source of creeping anxious dread. For one hundred nine USD it may seem a bit expensive for a sleep-exclusive device. For anyone thinking that, I’ll just point out that they hit all the core metrics, don’t lock anything behind a subscription, and for people who really enjoy the way cellphones killed the wristwatch only occupies a finger, and then only while sleeping. Consider picking one up from their US shop, or for international orders.

Everyone is forgiven for thinking a product named Amazfit is made by Amazon. Don’t think about it too much though because every Amazon device retains the complete un-massaged form of the name. It’s an Amazon Kindle Oasis, not an Amazbook. Amazfit is actually owned by a company named Zepp Health which explains the name of their devices iOS & Android app, Zepp. It’s noteworthy how hard they push Alexa in their ad copy anyway. Besides the Zepp app, I should note that the watch runs Zepp OS (version one, so a number of features found in version two are absent-more on that later), meaning you’re locked into their ecosystem as far as what is available on the device itself. That’s probably the reason they push the fact that there’s support for something as mainstream as Alexa. It looks like a slimmer, sleeker Apple Watch and it tracks sleep automatically. Supposedly that includes naps, although it didn’t pick it up when I laid down for an hour one afternoon. I had the same issue one night where I went to bed at sunset, slept for three hours, woke and had a bit of a run before laying back down a couple hours later around two. It did not include my second sleep, as a nap or otherwise. I wonder if that’s because I removed the watch to have a shower? Which is technically unnecessary, with it’s being waterproof and all, but what monster can stomach soap on a watch? Generally, it seems to detect sleep very well, reading before bed isn’t going to add an hour of sleep time, which is nice. This watch has an accelerometer, GPS, pulse oximeter, and microphone. Surely it has a microphone, how else would Alexa work? By using your phone? Alexa on the watch only works via Bluetooth tethering to a smartphone, but that does not include high jacking the phones microphone for audio commands to Alexa, those actually come from speaking into the watch. Given that relies on tethering it’s odd that it doesn’t have the option to use the phone to reply verbally, it responds in text on the watch face. Everything but the GPS likely comes into play for it’s sleep tracking, which is quite robust without a subscription to either their Zepp Aura Premium or Zepp Fitness Membership. For additional sleep tracking features the Aura subscription may be worth it. Priced at fifty USD per year, or just over four USD per month I’m seriously considering it though I expect I’ll hold off until I’ve tested additional devices. With a full color AMOLED touchscreen (there’s also a crown button that doesn’t turn like some more premium devices) display (it is a smartwatch after all) some sleep metrics can be viewed directly on the device. The sleep data is presented in two pages, with the first displaying total deep sleep time, sleep time, average nightly heart rate, and a sleep score. I rather like the score. All other sleep data, current and historic is only available in the app. Sleep has it’s own page in the app, with Home, Workout, and Profile being the others. Profile matters because that’s where various watch settings and preferences can be controlled, sensors turned on or off, that sort of thing. For sleep, there’s two specific toggles that may be turned on. First there’s assisted sleep monitoring which turns on or off automatic sleep tracking. Second there’s sleep breathing quality monitor that monitors breathing during sleep. It’s unclear if the way it monitors breathing is by pulse, oxygen saturation, movement, sound, or a combination of each. I expect it’s using all of them, just based on some of the information provided. Turning either of the sleep related settings on results in a warning that it will reduce battery life. It’s nice of them make the effort to be informative, but it’s also, like, duh. The advertised battery life is fifteen days. After ninety six hours battery life was at seventy percent. It’s nice to know one can spare a couple hours to charging one day each week and have no other concerns, even with all the default settings (pulse every ten minutes, auto brightness, raise to wake, display timeout at ten seconds) and the sleep and breathing monitors on. A final sleep adjacent feature which can be turned on is an intelligent alarm clock. It’s intelligent in the sense that it will alert based on sleep cycle at some point in the half hour leading up to the set time, or at the set time if it can not find an optimal sleep cycle in the prescribed half hour. The idea is that it less jarring than an indiscriminating alarm. The sleep page in the Zepp app is broken up first by period. I can’t speak to how normal my sleep stages are but it’s rare that I’m not awake already or in a light stage when the alarm time comes ‘round. The sleep data gets grouped as granular as day, and then steps back to show stats by week, month, and year. The year feels ambitious. Can a user be expected to carry on wearing the device for a year, or replacing it in the event of failure? If it’s found valuable enough, and it tries hard to be, it very well may. At the day level it provides a sleep score, and more interestingly provides some insight into where that falls among the ranks of their users; your score is higher than this or that percentage of our users. It’d be nice to know how many users that was. They then pitch a premium feature, a sleep health report including sleep apnea rush, insomnia, sleepiness, and restless leg syndrome. As I wrote above, I’m tempted. It does still call attention to various breathing concerns even without the subscription. Time asleep in hours and minutes is then shown and qualified (pay attention, good, and so on) and tapping it will show that data for the past seven days, a percent ranking among other users, and some condensed general knowledge regarding recommendations for duration. Next it shows the regularity of one’s sleep, how uniform the schedule is, and qualifies it. Then the prior week is graphed, as are the time to bed and the time up. Again it shows a short digest regarding the conventional wisdom on the topic. Next is a larger version of the sleep stages graph the watch presents. The graph is well arraigned in that with time on the x axis and stage on the y, one isn’t reliant on colors to differentiate the stages. Below that are cards for time and percentage of time spend in deep and REM sleep as well as awake and nap info. Each present the same week of history and relevant reading, as do the cards for heart rate and breathing quality. There’s also some presets to log pre-sleep state (read, music, phone, things like that) and emoticons to log one’s mood upon waking, a good habit to get into even if you’re not a monk. The weekly tab provides averages for the current week so far. I’ll note here that when a week is displayed it’s not a rolling seven days, it’s the week Monday through Sunday, not how I would chose to do it, but the days of history has to be broken up somehow. It’s not as nice as it could be, locking it to the Monday through Sunday period means a bad night early in the week can make the remaining days feel like a wash. What’s the point of trying to get a good nights sleep if you’ve already got two bad data points logged? The monthly tab steps back again and it’s graphs show data by week. Following that pattern the yearly tab breaks things down by month. What all these pages have in common is that they pair a users specific data, with percentage based assessments and information. The app might indicate that periods of deep sleep are on the low side, so it provides a card explaining what deep sleep is, why it’s important, and possible courses of action. Now, all of this is more of to do with the app, and not the device itself. About that, the Amazfit GTS four Mini is less a miniature GTS four, and more it’s own thing. For starters, it lacks a speaker like the GTS four, and a number of other features like audio playback or calling via Bluetooth. It’s also running a prior major release version of Zepp OS, one rather than two. This doesn’t really matter if sleep tracking is what’s desired. The major feature of Zepp OS two is Zepp Coach, without that it’s up to you to decide what your training days are and how intense any workout will be. That’s fine, personally I like the smaller size, it’s more proportional on my narrow wrist and with a smaller screen to support, and less features, battery life is better. I miss not having an audible alarm, but honestly, the vibration alarm is intense enough to be clearly audible as well. If you are interested in sleep, save a hundred USD and pick up the Amazfit GTS four Mini at ninety nine new and half that on the used market. If you want it to be a more robust gym-buddy spend more and get an Amazfit smartwatch that runs Zepp OS two. I also want to take a moment to say, Amazfit is a solid brand. If you aren’t looking for a Samsung, or an Apple device, it can be hard shopping in the smartwatch market. There’s a lot of brands out there that are cheap trash which make their money with a overpriced single sale of a device that’s made from the cheapest possible materials. They know they wont get return customers and base their business practices on that. Those companies aren’t building a brand, their selling the same device under half a different brands, that’s the only way they can get a return customer; fooling them into buying the same thing under a different name. That’s not Amazfit. Amazfit is a well-supported, functional, and quality option. Sure, Amazfit is not really competing with the six hundred USD and up devices. I do feel a brand new device from Amazfit is a better option that a four year old used device from one of the big two. Stop by the Amazfit US store, or hit one of their localized stores if you aren’t a fan of U.S. defaultism.

The Fitbit Inspire automatically tracks sleep with or without their nine dollar and ninety nine cent Fitbit premium subscription. The subscription model is very common in the wearable sector. It is a bracelet style watch, and it will display the hours slept from the prior night on the devices monochrome color touch sensitive display. For the Inspire (the first version, not the Inspire HR, two, or three which all measure heart rate) it has no specific sensors apart from an accelerometer by which to identify the sleep. It seems to take several minutes to trigger and it invariably counts the initial minutes as awake or restless. There’s probably some back dating going on as laying down at twenty two hundred hours on the dot it immediately clocked sleep as beginning at that time, not three minutes past the hour as one would expect if it did not begin tracking retroactively. It does not detect sleep if it’s removed and left perfectly still for a long period of time, so it distinguishes between being worn and detecting sleep by stillness as opposed to perfect stillness. If a period of time is spent laying in bed it will invariably count sleep as having begun too soon. Don’t go to bed with a book to read for an hour, or at least not with a Kindle where the motion to turn a page is confined to a button or touch. During sleep, and without a premium subscription, it does not register any different phases of sleep, such as light, deep, or REM, only awake, restless, or asleep. A premium subscription unlocks sleep stage tracking and an aggregate sleep score. The score is dependent on heart rate, and as the Inspire does not measure heart rate it is unclear if a score would be calculated. More than likely it would still provide a score but it would be based exclusively on periods of awake and restless versus actual sleep time. What counts as sleep as opposed to awake or restless is a black box. I wake up several times whenever I sleep. Out of habit I do my very best to remain in bed when it happens because if I get up history proves I’ll stay up. I am generally successful at falling back asleep, eventually. Only if I get up does it seem to register wakefulness as awake. Trip to the kitchen or bathroom? awake. Roll over and over five times in twenty minutes? restless. I had the thought that pressing the side button to wake the display and paging through the various datapoints it shows would cause it to register awake instead of restless. It did not, but that was probably an optimistic thought for a product that was seventy USD new in two thousand nineteen and twenty USD used today. It tracks sleep only as well as is necessary to tick that check box when competing against other devices, or that’s my impression of it’s depth at least. Battery life was at sixty percent after ninety six hours so a full week on a single charge may be expected. Charging is via a proprietary USB cord that has a three contact magnetic coupling on one end and a male USB A connector at the other. In the free iOS or Android application data for time asleep is presented in both a horizontal and vertical bar graph with days of the week on the one axis and seven days shown at one time. The vertical graph pretty exclusively shows hours slept. The horizontal graph presents the total time asleep and marks the bar with lines indicating restlessness and wakefulness. For any individual day there’s an additional chart with hours on the x axis with lines of various width denoting restless periods in blue and awake periods in red, it’s a zoomed in expression of the horizontal graph. Underneath, it breakers out the time asleep, time at which it’s clocking you as asleep and awake, and the total count of periods of both, and finally the total time not spent asleep. In the most annoying design decision possible it places the prior night of repose under the heading Today. Fortunately it does at least put that prior evening under the previous day’s day of the week. If it’s Tuesday, it will say you managed five hours of sleep Today, but it will put an M for Monday under those hours in it’s bar graph. A subscription may change how the data is presented, and it the depth of that data. It’s worth noting that Google owns Fitbit, which means a Fitbit Premium subscription is indirectly paying for Google, which is, frankly, something I’ll never choose to do. If they don’t earn enough showing me advertising to provide more in depth sleep tracking for free, that’s on them. As far as devices go this is certainly one of the cheapest options, provided buying used is on the table. It’s not likely to be something that gets fiddled with, just because it’s so simple. I’m sure the expectation is that it will be worn unless it’s charging. There’s little reason to do that though if one is only interested in sleep, and there’s few features other than step-counting that might justify it. It’s rather sleek, if unfashionable, and should fit under most sleeves if that’s any concern. Is this a tracker worth picking up? No. So why a review? I had one purchased during COVID as a means of incentivizing activity. Hit the Fitbit store if you have an interest.