The Rise of Sleep Data Enthusiasts: “The Harder You Try, the Harder It Is to Sleep” | Sleep

TThe first thing Annie and her partner do when they wake up in the morning is ask themselves if they slept well. “And I literally say, ‘I’m not sure yet, let me check’” – and Annie, HR and security manager, picks up her smartwatch.

Annie began monitoring because she was concerned that she was not getting enough, good quality sleep. Today, she’s a self-confessed sleep data “enthusiast” who mines her sleep data for insights into her overall health and well-being, uses it to inform her lifestyle decisions, and even occasionally to determine what she wants to accomplish in a day.

Sleep monitoring is a growing industry, much like what devices and apps like Fitbits and Strava have done for physical activity. Market reports vary on the value of this industry, but it is clearly lucrative and growing rapidly. A quick search reveals a wide range of devices – rings, headbands, watches and other wrist-worn devices, under-the-mattress devices and bedside devices – all suggesting that their use will unlock such quality sleep that it would make Rip Van Winkle jealous.

It is estimated that 40% of Australians do not get good quality sleep and one in ten suffer from chronic insomnia. “We know that many people are concerned about their sleep and whether they are getting enough sleep, particularly if they are not meeting some of the recommended sleep duration guidelines,” says Dr Hannah Scott, a senior researcher in sleep psychology at Flinders Health and Medical Research Institute in Adelaide and co-inventor of a wearable device that tracks and treats chronic insomnia.

Scott sees the increase in use of sleep trackers as good news overall. “They definitely increased awareness of the importance of sleep and healthy sleep habits, so overall I would say they probably had a positive effect.” But there is a downside. “If you try harder to exercise, you’ll get fitter, but we actually have the opposite problem with sleep: the harder you try, the harder it is to sleep,” says Scott. “We can create problems if people become too obsessive in trying to optimize it.” There’s even a term for it: orthosomnia, which describes an unhealthy preoccupation with sleep tracking data.

The most accurate picture of sleep health is derived from something called polysomnography, which requires a person to spend the night in a sleep laboratory with their head and body covered in electrodes that monitor and measure brain wave activity, eye movements, breathing, heart rate, muscle movements and blood oxygen levels. This provides a wealth of information such as how much time is spent in different stages of sleep, how many times a person wakes up and how long it takes them to fall asleep, says Professor Christopher Gordon, professor of sleep health at Macquarie University in Sydney.

“Wearable devices – and this lumps a lot of different devices into one word – but in general they’re not as accurate in being able to tell how long it took you to fall asleep and how long you were awake and asleep during the night, and that’s because they don’t measure brain wave activity,” he says. This brain wave activity is used to determine the time spent in the different stages of sleep: stages one, two and three of non-REM sleep and REM sleep.

What wearable devices can detect and measure – in various combinations and with varying degrees of precision – is heart rate, temperature, movement and blood oxygen levels, which are then fed into algorithms that determine whether the picture painted by this data is that of a person in deep sleep or restless. “It could be a device that specifically measures just movement and looks at algorithms that say if your arms move a lot you’re awake, if they don’t move a lot you’re asleep,” Gordon says. But “it has very little to do with what’s going on in your brain in terms of the quality aspect of sleep.”

The other challenge is that there isn’t a clear understanding of what exactly good sleep looks like, says Associate Professor Jen Walsh, director of the Center for Sleep Sciences at the University of Western Australia in Perth. “It’s a subject that is debated within our profession,” she says. There is sleep quantity – simply the time spent sleeping – and sleep quality, which is more complex and takes into account how much time is spent in different stages of sleep, whether sleep is interrupted, how often and for how long. “Sleep quantity is fairly easy to define and calculate, while sleep quality is a little more difficult,” she says. Current guidelines suggest adults should aim for between seven and nine hours of sleep per night, but there isn’t as clear guidance on what type of sleep (the amount of each stage) is optimal.

Sleep quality is also very subjective and sometimes doesn’t match what even the most accurate laboratory monitoring says, according to Dr. Maya Schenker, a postdoctoral researcher in trauma and sleep at the University of Melbourne. “If we feel like we slept very poorly, it doesn’t matter what the watch tells me,” she says. Even among people with chronic insomnia, sleep often appears much better on polysomnography than they subjectively report.

Consumer sleep trackers have one advantage over sleep study polysomnography: They are used every night for extended periods of time. “A night in a sleep lab only gives you a single snapshot of that night, but it’s not necessarily a reflection of every night that you’re at home in your own bed without wires attached,” says Walsh.

Rachel says her sleep monitoring ring has helped her understand some of the factors that help her get a better night’s sleep. “If I do Pilates in the evening, I seem to sleep better,” says the Canberra-based civil servant. And Annie noticed that if she drinks a glass of wine at any time during the evening, her heart rate while sleeping is about 10% higher.

This is where most experts see the usefulness of sleep trackers in a consumer context: helping people understand how their lifestyle habits and behavior affect their sleep and making changes to improve it.

“Many people want to change their sleep habits, but it’s difficult to find where to start,” says Dr Vanessa Hill, a sleep scientist at the Appleton Institute at CQ University in Adelaide, who also consults for Samsung Health. Data alone isn’t usually enough to change behavior, but “if your watch can send you a notification like ‘hey, yesterday you went for a walk at this time and it improved your sleep,’ or ‘yesterday you stopped drinking caffeine at this time’ or whatever, and it helps you fall asleep faster,” that can motivate people to change, she says, “I think that’s the greatest potential that these types of trackers have to have.

Hill uses a smartwatch and ring to monitor her sleep and says she checks her sleep scores — particularly her heart rate during sleep, which she says can predict impending illness — as soon as she wakes up. “I look at what they did during the night, because if I get sick or catch a cold or something, my heart rate variability will tell me before I feel any symptoms myself,” she says. “If for some reason I have really high heart rate variability one night, I just tell myself I need to take it easy today, something is wrong with my body.”

Many experts point out that consumer sleep trackers are not diagnostic tools and have significant limitations. “If you train an algorithm on a defined healthy population, you’re not necessarily going to pick up the same signal in a population with, say, peripheral vascular disease with reduced blood flow in the fingers,” says Dr Donald Lee, a respiratory and sleep physician at the Woolcock Institute of Medical Research in Sydney. Sleep patterns also change over the lifespan, which may not be reflected by the algorithms used.

However, sleep trackers offer the opportunity to encourage healthier sleep habits, says Lee. “If we can get people to… go to bed with a purpose, turn off the lights, fall asleep, and improve their sleep habits by engaging in conversation, that’s a good thing for health trackers to do.”