Sleep trackers: Living the dream

If you think your Fitbit can track your sleep properly you’re living in a dream world

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If there's one feature of wearable tech that gets readers riled up over at Wareable, it's the curious notion of sleep tracking. Yet I've never understood what the fuss is all about.

When the first fitness trackers arrived on the scene, it wasn't the health boosting potential, or opportunity to make you walk yourself happier that caught the imagination – it was their ability to unlock the secrets of your sleep.

I admit, I too was drawn to the idea. What exactly happened in those lost hours? Did I secretly fight crime on the streets of leafy South London? Did I sleepwalk?

I quickly realised two things. Firstly, I was not a nocturnal Dark Knight, and secondly, the data harvested by my plethora of sleep trackers was meaningless.

Quickly – within a week – my interest diminished as it became clear that my fitness band had as much idea about the nuances of my sleep stages as the loud crow that visits my rooftop at 5am each morning.

The thing is, sleep is an enormously complex biological function, and no band strapped to your wrist is able to unlock its secrets. Most fitness trackers are simply armed with an accelerometer, capable of tracking slight movements. From there it guesses whether you're in a deep sleep (little movement), a light sleep (some movement) and REM sleep (no movement).

Professor Paul Gringras, lead consultant at the Evelina Clinic at Guy's and St Thomas' Hospital is one of the top sleep clinics in the UK, and he told Wareable that claims of tracking sleep stages with a movement sensor on your wrist are largely snakeoil.

“The only way to tell what stages of sleep a person is in at any moment is by attaching electrodes to their heads to measure their EEG," explained the Professor.

If the irrational guesswork of sleep trackers wasn't bad enough, another fallacy is the idea of the smart alarm. If you're not familiar, the idea is simple. If you're in a light sleep 15 minutes before your alarm goes off, it will gently awaken you, rather than haul you from a deep slumber 15 minutes later, making you feel fresher.

Absolute rubbish. Again, don't take my word for it – as Gringras confirmed that while waking from a deep sleep can be unpleasant, it's far better for your health and wellbeing to get the most sleep you can.

“We're getting up earlier than we probably should, having not quite had as much sleep as we're biologically designed to, and it's cumulative. So, if you lose half an hour a day, that's three and a half hours over a week and that's enough to set back your learning and memory significantly. For a child, that's equivalent to a year's learning. So, it can be quite significant.”

The argument about most elements of fitness tracking is that the data isn't designed to be a scientific analysis of your body. While a Fitbit might not track every step of the day, it's good enough to show you a representation of how active you are.

While a sleep tracker might not be able to accurately deliver the insights into sleep that it promises, isn't the vague idea of tracking how many hours you're getting helpful? In some cases it can be, and if that number helps you change your habits to hit the hay earlier, then it's done its job.

However, for those who struggle to sleep, the presence of a tracker can be an extra inhibitor to a restful night's sleep. In the words of Prof. Gringras:

“If someone's developing insomnia, the very last thing they want is to be hypervigilant, counting every good or bad minute, because that will make you worse."

So sleep trackers are largely unable to track our sleep reliably, their key features probably negatively affect our health in the long run and in some cases, could stop you sleeping properly at all. So should they be consigned to the scrapheap of wearables?

Not so fast. And I believe there is a place for sleep tracking.

There have been some breakthroughs with using heart rate detection – and the Withings Aura is one such product that gets a lot right. Reading your heartbeat from beneath the mattress, the Aura can better estimate your sleep cycles, and show you an accurate graph of your resting heart rate (a good indicator of health) and tell you if your room is too hot or cold.

Yet again, the product still illustrates my point about the lack of usefulness. For a product that knows you're asleep, it won't wake you up if you sleep through its own alarm. It doesn't even have a snooze function.

And there are other examples, too. Misfit has talked about its Flash tracker talking to Nest thermostats to automatically put your room temperature for the optimum temperature for a good night's sleep.

It all illustrates there is a future to sleep tracking, and there are useful applications which could help in every day life. But you can't teach me how to sleep better.