ResMed S+

How much do you want to know about thinks that go ‘zzz’ in the night? A lot it seems. Sleep monitors are probably one of the gadgets I get asked about most often. So it made sense to test the one that looks like none of the rest. The ResMed S+.

Instead of a wearable, the ResMed S+ is a pretty slab of plastic that sits on your bedside table, scanning you wirelessly (using radio waves) and streaming data to your phone. It has additional sensors for light levels and noise. Power comes from a (supplied) 5v micro-usb charger which has a handy second port for charging your phone.

Set up is fairly simple. Pop the unit on your bedside table and point it towards you then pair via Bluetooth with the app from your preferred store (OK, the only one available to you). Pairing took us a couple of attempts and it’s not always clear from the app that you don’t need to re-pair: the symbol for the device turns red when it’s not connected, leading me to go through pairing again a couple of times. But once paired it actually connects when it needs to — e.g. when you activate sleep tracking (more on that later).

The app will ask you some details about yourself and your sleep, and some have reported concerns about what happens to this data, as well as the sensor output. After all, it may not be a camera in there but there’s enough sensing capability to identify more than sleep. But the manufacturer’s privacy policy is reasonably conservative about the circumstances in which it will share the data. You pay your money, you take your choice.

Time for Sleep

When it comes to actually go to sleep, you have to tell the unit that’s what you’re doing. Tracking is only started after you have hit a ‘Sleep’ button in the app and answered some questions about your day. I understand the mechanics of this: the questions are an important part of the diagnosis process that the app is trying to undertake. But this manual interaction seems rather incongruous. It’s what sets the S+ apart as a diagnostic device rather than a lifestyle device.

In the morning the app provides you with a breakdown of the previous night’s sleep: how long it took you to fall asleep, any interruptions, and the periods of light, deep, and REM sleep you went through. This is all fed into a sleep ‘score’, giving you a general idea of objectively how well you slept.

The data I saw from the S+ was richer than the other activity-monitor-based sleep tracking I’ve seen and seemed to tally most nights with my subjective experience. There was one exception where the system thought it had taken me 44 minutes to get to sleep, when it felt more like 40 seconds. This undermined my confidence slightly but these sorts of occasional blips would even out over enough nights to get a clear picture.

Collect a few night’s data and the system will start to offer tips to improve your sleep. Overall my sleep was pretty good: typically upwards of 75/100. But the graphs of my sleep pattern each night showed that I was missing a big chunk of deep sleep. This was what I naturally wanted to focus on since it was the biggest factor in depressing my score. But the tips seemed largely focused on the previous night’s experience rather than the overall: interruptions and how long it takes to get to sleep. I’d have loved to have seen some deeper analysis of the base pattern over the topical issues.

ResMed S+: Analysis over Maintenance

The ResMed S+ is probably the most sophisticated sleep tracker you’re going to get outside of a lab. Its sensor readings seemed to largely fit with my subjective experience, with only the one exception, and the richness of the data it produced were genuinely intriguing. If you want to know why you’re a wreck in the mornings, this might be a great place to start.

However it’s not a lifestyle device: the lack of automatic tracking means you have to decide to monitor your sleep, and after a week I found I just didn’t bother turning it on. There may be privacy issues with an option to collect data automatically, but I’d be inclined to turn it on in order to have the data at hand. You can always point it at the wall when you don’t want it watching….

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