Wearable technology has boomed in the last few years, and quite understandably: when it comes to monitoring your activity, wearable devices are a no-brainer. But sleep monitors are a little more complicated.
More and more people subscribe to the concept of the Quantified Self - using data to interpret our lives, rather than philosophies or ideas. Wearable devices generally, and sleep monitors particularly, align nicely with this school of thought.
Until not so long ago, the only way to monitor your sleep was to get medically checked at a sleep clinic. Sleep clinics use a multitude of devices to determine the quality of your sleep, which wearable devices cannot compete with in their current form. But many people are singing these devices' praises. So what is the right answer? Do sleep monitors actually work? And if so, who are they good for?
Why is sleep important?
In order to properly delve into these questions, we wanted to understand more about sleep in general. Most sleep scientists divide sleep into 4 main stages: Stage 1, 2, 3, and REM.
- Stage 1 is the choppy part at the start of your sleep. You don't spend much time in that phase, and therefore most sleep monitors forego taking note of it altogether.
- Stage 2, or Light Sleep, is the main part of your night's sleep, comprising of more than half the night. In this stage, your body is asleep but can easily be woken up, and it allows your body to process memory and emotion, as well as help your metabolism.
- Stage 3, or Deep Sleep, is when your body starts repairing itself. It secretes growth hormones which help your cells rebuild and your body to revitalise.
- REM sleep is when you dream. It allows your body to regulate your memory and emotion, and also synthesise protein.
Your sleep works in cycles, but most of your night will be spent in light or deep sleep.
How do sleep monitors measure your quality of sleep?
In an experiment published by the Huffington Post, Dr Christopher Winter, a sleep specialist, compared multiple sleep devices while monitoring his sleep in an actual sleep clinic using medical devices. He then contrasted the output from the sleep lab and the devices he was wearing.
Some sleep monitors provided similar results to the medical test, while others didn't. Overall, it was very clear that these devices provide less detail than the sleep lab, since they only track movement (and in some cases, heart-rate). You can, however, learn some basic information, and with certain devices, it was pretty accurate information too.
But the main power of these monitors isn't necessarily the amount of detail they can provide - it is about the consistency of tracking that cannot be achieved with regular sleep medicine.
The routine of tracking your sleep every night can psychologically make us want to do better, Dr Winter explains. This means going to sleep earlier, avoiding caffeine or screens before bed, and doing anything possible to get a better night's sleep. That's a huge benefit in its own right.
As to the accuracy of sleep monitors, there are some issues studies have raised. For example, wearables assume that moving around a lot equals being awake or in a lighter state of sleep. This is true for a lot of people, but also false for others - some of us are just naturally restless sleepers.
It works both ways: trackers may overestimate an insomniac's sleeping time, as they tend to stay still for long periods without being asleep.
Scientists' main concerns about trackers are not only about the accuracy of what they measure, but also about what they don't measure. Some of us may have underlying sleep problems that might be ignored by conventional sleep trackers - and others may not have them, but be made to think they do after tracking their sleep.
Another real danger is that some trackers, according to a Harvard study, have "optimistic marketing claims" which they cannot fully stand behind - this can be particularly harmful when it comes to medical sleep concerns such as sleep apnoea or periodic limb movements.
But if you don't have any medical sleep disorders, the researchers at Harvard came to the conclusion that sleep trackers can have great benefits. By using a sleep tracker, you can learn more about how your sleep is affected by your behaviour and experiences (for example, alcohol and caffeine consumption, stress or exercise) on the one hand, and how your function is affected by your quality of sleep on the other hand. The researchers go as far as saying that "such data could be powerful across the spectrum of wellness and health".
So, should I get a sleep tracker?
The simple answer is: it depends on what you're trying to achieve.
If you have actual medical concerns about your sleep, sleep trackers should not be your first stop - the doctor's office should be.
However, if you just want to improve your sleep, or if you're merely interested in finding out more details about it or tracking your sleep for any reason, sleep monitors can be a great option.
I like the idea! What should I look for in a sleep monitor?
There are many types of sleep monitors: under-mattress, under-bed-sheet, bedside table, phone, wearable and even T-shirt form! Each format has its own pros and cons: for instance, mattress-based and bedside monitors tend to be less accurate when you don't sleep alone or if you move a lot during your sleep, while wearables are generally less comfortable to sleep with.
If you want to check out sleep trackers without the hefty price tag, you can always start with a phone-based tracker such as Sleep Cycle. They can definitely satisfy the need of most sleepers, or at least be a great place to start.
Once you've decided which format you feel would best suit your needs, look into the different options. There are so many sleep monitors around, with varying levels of detail and parameters (movement, heart-rate, noise, light etc.). Don't be tempted to go straight for the most detailed version, because you may not need it (and as a rule of thumb, the more detail you get, the more you will pay). Our top tip is to decide what you hope to achieve by tracking your sleep and try to get a device with the best-suited spec for your needs.
Most sleep wearables double as health activity trackers, so if you choose this option you may want to take a look at what your desired monitor can do for you on that part too.
If we want to narrow it down to three things you should compare when searching for a sleep monitor, we would choose: how comfortable it is, what it tracks, and how long the battery life is (and how it's charged).
Whatever you choose, just make sure it works for you - everyone has their own preferences and a device that might be super functional for one person can be another person's sleep tracker of nightmares. We hope your sleep monitoring journey will help you reach the stars!