leep tracking has become an important piece of total wellness monitoring, but typically requires strapping devices to your wrist or head. Withings Sleep Analyzer records your sleep and heart rate, plus is one of the first devices to monitor sleep apnoea, all without you needing to attach anything to your person. Instead, the £120 Sleep Analyzer is a sensor-packed slim mat that you slide under your mattress. Once it’s there you simply go to sleep as normal. The mat is 637mm long, 190mm wide and only 5mm thick, so easily slides between your mattress and base (including slatted bases), positioned around where your chest lies. It tracks your breathing, heart rate and movement with a pneumatic sensor, and your snoring and sleep apnoea with a sound sensor. It then syncs the data via wifi to your Withings account and the accompanying Health Mate app when you get up. Set up is simple using Health Mate on iOS or Android. Put the mat in place, plug it in, find the mat via Bluetooth in the app and then wait for it to inflate and calibrate. The process takes about five minutes. You can’t feel it in bed and can barely see it, as just a thin USB power cable pokes out from under your mattress, which plugs into an adapter. The cable is long enough to stretch to the nearest plug, even if it’s on the other side of the bed. The tracking is automatic, so all you have to do is get into bed and sleep as you usually would, which is the beauty of the Sleep Analyzer system. You can completely forget about it and just pick up your data when you need it. Sleep Your data is securely synced and stored in your Withings account, but can be synced from there with other apps and combined with fitness data such as steps from Google Fit and Apple Health, among others. You get a colour-coded graph showing your periods of being awake, in light, deep and REM (when you dream) sleep over time, an overall sleep score each night out of 100 and a rating in words, such as “restful night”. But you also get data broken down into sections including duration, depth, regularity, the number of times your sleep has been interrupted, the time it took you to go to sleep and the time it took you to get up after waking. Each section has a traffic light system: green dot for good, orange for average and red if it’s been a bad night. They can be expanded for more information, too, such as a range of what was good and bad, comparisons with previous nights and some simple advice. Those are the basics of most sleep trackers and the Withings matches the data from various other wrist-borne sleep trackers including Garmin and Samsung watches pretty well. The Health Mate app presents the data in a way that makes it fairly easy to follow what happened overnight, and gives an average of sleep scores and sleep time over the last week or month. What it doesn’t do is provide much in the way of guidance on how to improve your sleep beyond the most obvious things, such as maintaining regular hours, keeping noises to a minimum in the bedroom and the temperature low. Heart rate Beyond basic sleep stats, the Sleep Analyzer also measures your sleeping heart rate, with an accuracy matching wrist-borne heart rate monitors, as a good measure of overall health: the lower the better to a point. You can see a chart of your heart rate for the night, but also see the trend over the last quarter. My average sleep heart rate has decreased by two beats a minute over the last quarter, for instance. Here Withings has more advice covering health, fitness, diet and other bits, which can help you find out why your sleeping heart rate might be high. You can also spot things in your own charts. I can see, for instance, when I’ve been ill as my sleeping heart rate is higher than normal across the full night, or when I’ve drunk alcohol in the evening as my heart rate starts higher then tapers back down to normal as the night progresses. Sleep apnoea and snoring The Sleep Analyzer’s killer feature, which few other devices can offer, is tracking of sleep apnoea, something Withings recently got regulatory approval in the EU to implement. Sleep apnoea is a condition where breathing becomes more difficult when you’re asleep due to the relaxation of the muscles in your throat, which can lead to you to stop breathing. The result is a disturbed sleep where you’re often jolted at least partially awake to breathe again. For many this may happen occasionally in the night, but for some it can happen as much as 20 times an hour, which does your sleep no good at all. Many may be completely oblivious this is happening too. Each night the Sleep Analyzer watches for signs of sleep apnoea, recording events as well as snoring, which can be a precursor. The data is then presented to you on a sliding scale of normal to mild, moderate and severe. My highest over the last couple of months has been 11 events an hour, which was rated as normal to mild, but most nights are symptomless. I also don’t snore very often, but when I have the tracker has picked it up reliably. You can view your data over the last day, quarter or year, to keep an eye on it. But if the tracker detects enough sleep apnoea events it will recommend a couple of tests to estimate your risk, give you guidance on the symptoms, advice on how to improve things and lets you share a report with your doctor should medical help be needed. It’s worth noting that some wrist-borne fitness trackers with blood oxygen sensors can also track sleep apnoea events by measuring the dip in oxygen in your blood associated with them. Observations The mat turns off its wifi connection when you’re in bed. It makes a whirring noise if it needs to reinflate after adjustment. The mat can be powered by most standard USB chargers. Two mats can be used in the same bed to track the sleep of two people. Price The Withings Sleep Analyzer costs £119.95. For comparison, the previous Withings Sleep cost £99.95 and Apple’s Beddit Sleep Monitor costs £149. Many fitness trackers starting at about £35 can also track sleep as can smartwatches, including the Apple Watch, Garmin Forerunner 245 Music and Samsung Galaxy Watch Active 2 costing £200 and up. Verdict The Withings Sleep Analyzer is a sleep tracking mat that’s simply easy to live with. Stick it under your mattress and go to sleep. It works automatically. You can’t feel it, nor do you have to wear or charge anything. The data it produces is good and the way it’s presented in the excellent Health Mate app is easy to follow and track across days, weeks or quarters. Sleep heart rate data is interesting and the ability to track both snoring and sleep apnoea without having to wear anything is the mat’s killer feature. The app provides some good information around heart rate and sleep apnoea, what it means and how to improve it, but it could do with some more effective guidance on how to turn around a trend of bad sleep, rather than letting the user work it out from graphs and stats. With sleep tracking built into many wearables, you might wonder why you need a purpose-built gadget for it. Really the Sleep Analyzer is for those who, like me, don’t like wearing devices or watches overnight. It’s not cheap, but the Withings Sleep Analyzer works great with the minimum of fuss if you want to track your sleep. Pros: comprehensive sleep tracking, nothing to wear, very easy to live with, fits most beds, tracks heart rate, monitors sleep apnoea, syncs over wifi Cons: expensive, guidance on how to improve sleep could be better