It’s becoming a well-known secret that sleep is the key to a healthy, productive and happy life. The 7-9 hours of sleep per night isn’t just an arbitrary amount, but rather an amount that’s natural for us and always has been. The only argument (or excuse) you ever need for making sure you get enough sleep is this quote from Matthew Walker in his book Why We Sleep (one of the most influential books I’ve ever read):
Evolution would remove all traces of sleep if it wouldn't be so important, don't you think?
Tech is once again making sleep assessments available to the masses. 5 years ago, you needed to go to a sleep lab and do a polysomnography (PSG) to assess your sleep. While that’s still the most accurate assessment, it’s just not accessible. Consumer devices, on the other hand, offer a viable and affordable alternative.
No matter how you look at it, a wearable device is nowhere near as accurate as a PSG. The difference is that PSG measures EEG, eye movement, EMG and ECG during sleep. It measures it directly. Wearables, on the other hand, use different sensors such as the accelerometer, HR monitor, some even breathing and SpO2, to predict the sleep stages and duration. But if you think about it, by using the same tracker every night the same error is done every time. So, you get good feedback on the quality of your sleep compared to previous nights.
The way I visualise the sleep tech market is like this: the basic, the advanced and the aids.
In this category fall the simplest trackers for sleep - predominantly all kinds of wearables. Most fitness trackers nowadays use HR monitors and accelerometers to determine the length of sleep and its phases, which is usually a useful approximation. For example, this is how you can determine the window that suits you best. If you figure out you feel at your best when sleeping from 11 PM to 7 AM, that’s the way to do it. Simple as that.
Perhaps a more accurate measurement is with the Oura Ring. It’s one of the few trackers that also measure body temperature. As the human body temperature decreases during the night and is at its lowest point just before waking up, this is also a useful value to track.
It goes one step further with oxygen saturation monitoring (SpO2), which is very useful for detecting sleep apnea. SpO2 is most notably now also a feature of Apple Watch 6. However, it’s not FDA certified because Apple claims this sensor is just for general wellness and not for diagnosing diseases. So, it isn’t certified for detecting sleep apnea, but it does background measurements during sleep. I imagine this can give you some useful information on what’s going on with your breathing during the night and act accordingly. The noise has been made primarily because it’s Apple and because it may be useful for tracking the development of Covid-19.
On the other hand, there’s Withings ScanWatch, which I briefly mentioned in issue #27. It also features a SpO2 sensor and is even used in a Covid-19 clinical trial at LMU Munich and other. When it makes the first SpO2 measurement during sleep, it determines how often it will be performed. This gives you a little insight into sleep apnea episodes such as snoring and a basis for further steps. Their sensor has been clinically validated, is expected to get FDA clearance, while already possessing the CE medical certification in Europe.
The “gold standard” of consumer sleep trackers also comes from Withings and it is their Sleep Tracking Mat. It’s an actual a mat that you put under your mattress and you’re ready to go. This is more comfortable and seamless than even having a smartwatch on your wrist. The sensors inside the mat are reportedly advanced, yet so useful. All of them combined track sleep cycles, heart rate, breathing rate and snoring, which once again gives the users an idea whether they’re experiencing any sleep disturbances.
Then again, it doesn’t end there…it goes one step further. Last week, I included a link to a company named EightSleep. They make full-sized mattresses that measure similar parameters as the Withings Sleep Tracking Mat. However, the mattress can be cooled down to ensure the body is thermoneutral. This is important as a rising temperature can wake us up too soon. The idea is awesome, but it’s about 20x more expensive than the Sleep Tracking Mat.
Another advanced gadget for improving sleep is called Dreem. It’s a headband that is the closest thing to a PSG - a consumer EEG, with an HR and a breathing monitor. The advantage they have is that people don’t need a doctor to interpret the results, once again democratising health data. On the other hand, as far as I could find out, they aren’t clinically validated, which still doesn’t exclude doctors from the process. And that’s a good thing. For the record, their device is used in several pieces of research and was already featured in a couple of papers. It’s worth paying attention to them and seeing how they develop this product!
This is probably the most controversial part of this issue, as there just isn’t a good sleeping aid out there - no matter how you look at it. Whether pharmacological or technological. The more pharmacological (ish) part was covered in issue #21, but I haven’t written about tech yet.
The most promising results for “generating” sleep are by electrically stimulating the brain. Let’s let Matthew Walker explain it once again:
In this study, the participants, whose brains were stimulated, generated more sleep spindles and could remember more facts than the control group. This only appeared when stimulating non-REM sleep, while showing no benefits in REM sleep and wakefulness. The method is called “transcranial direct current brain stimulation” (tDCS). However, there are no consumer products available for this, at least not certified ones! From what I make, Johns Hopkins Medicine uses this method for treatment of various disorders, but not sleep.
Another option for improving sleep with outside factors is also auditory stimulation (or relaxation) but this once again shows mixed results. It usually disrupts sleep, no matter what the apps and gadgets are saying.
The quality of sleep isn’t up to the consumer gadgets. It’s up to us to take the data and use it to change our behaviour to improve our sleep. Whether that's food, meditation, phone usage, sleep schedule or anything else. There are no shortcuts…for now.