Sleep is important for health and wellbeing, and if we don’t get enough sleep, it can impact our productivity and mood, as well as increase our risk of health conditions like cardiovascular disease.

So, it’s not surprising that sleep tracking has gained immense popularity in recent years as widely accessible wearable devices like Fitbits, Oura Rings and smartwatches promise insights into our nightly sleep.

Senior man analysing his sleeping data from smartwatch — Sleep trackers tend to overestimate total sleep time and underestimate wakefulness after falling sleep. Picture: Getty Images

But are they helpful for understanding and improving sleep, or could they potentially be harming our sleep?

The answer is both – when used correctly they can help us manage our sleep patterns, but for some they can enhance sleep anxiety or lead to orthosomnia, which is an unhealthy obsession with getting the ‘perfect’ sleep score.

There are sleep trackers, and then there’s polysomnography

Sleep trackers primarily rely on data from movement sensors called accelerometers to work out whether someone is awake or asleep. If you’re not moving, the device thinks you are asleep, and if you are moving, the device thinks you are awake.

Some newer devices also use your heart rate to help infer different sleep stages, like deep sleep and REM (rapid eye movement) sleep.

This differs greatly from the scientific gold-standard sleep study tool, known as polysomnography – or PSG for short.

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PSG measures your brain waves, muscle activity, eye movements and heart rate. Oftentimes additional recordings are made as well to capture breathing, oxygen levels, chest and abdominal movements, leg movements, body position and even snoring.

PSG sleep studies document very rich and comprehensive sleep data which can be used to diagnose sleep disorders like obstructive sleep apnoea.

However, PSG sleep studies often require an overnight stay in a sleep laboratory, and can be expensive, requiring a GP or sleep physician referral. They also only report on one night of sleep – which isn’t necessarily representative of a person's typical sleep at home.

Sleep trackers, on the other hand, are accessible and relatively inexpensive. You can wear them every night, allowing you to capture your sleep patterns over time.

But these trackers make assumptions that can lead to errors and are generally not suitable for diagnosing sleep disorders.

A recent comprehensive review of sleep wearables found that consumer-grade sleep trackers vary widely in their ability to accurately detect sleep stages, particularly deep sleep and REM (rapid eye movement) sleep.

Patient sleeping in a medical clinic doing polysomnography (sleep study) — PSG measures your brain waves, muscle activity, eye movements and heart rate. Picture: Getty Images

In fact, some devices only manage 50 to 70 per cent agreement with PSG-measured sleep stages.

Sleep trackers tend to overestimate total sleep time and underestimate wakefulness after falling sleep. For instance, in some cases, wearables misidentify being awake as light sleep, especially if you remain still.

Our work found that sleep trackers do not yet have strong enough agreement with gold standard sleep measurement to replace clinical sleep evaluation and sleep studies.

Can a sleep tracker help me sleep better?

Sleep trackers are best used to give a general sense of how much sleep you get on average over time, rather than a precise breakdown of sleep stages.

Many people skimp on sleep to increase their work hours, spend time socialising or relaxing, or to get up early to go to the gym.

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So, for good sleepers without significant sleep complaints, sleep trackers can be helpful for tracking whether you are getting adequate sleep, which is, on average, seven to nine hours per night for adults.

They can serve as a tool for establishing a more consistent sleep schedule or noting patterns in lifestyle factors, like exercise or stress. For instance, a generally good sleeper might find it helpful to see how habits like regular exercise are impacting their sleep.

But unfortunately, the accuracy of sleep trackers tends to decrease for people with sleep problems, and sleep trackers may even hinder rather than help them sleep.

People with insomnia often have disrupted sleep and increased movement during sleep, which these devices can misinterpret as lighter stages of sleep or wakefulness, respectively.

This means that sleep trackers may report that you get less sleep than you actually do. This can increase stress and worry about sleep – which, of course, can make it harder to sleep.

A polysomnography read out on a computer screen — Polysomnography (or PSG) is the scientific gold-standard sleep study tool. Picture: Alamy

Alternatively, if you are lying in bed awake but very still, a sleep tracker may overestimate your total sleep time.

Tracking sleep through a wearable device can also sometimes lead to a new sleep phenomenon called orthosomnia.

The perfect sleep, or the perfect sleep data?

Orthosomnia, or the obsession with achieving ‘perfect’ sleep data, was first reported by researchers from Chicago in 2017. It refers to a person becoming fixated on sleep tracker metrics, interpreting small deviations as indicators of sleep problems.

This can lead to sleep-related anxiety which, ironically, worsens sleep. When hyper-focused on our sleep tracker data, some people may spend excessive time in bed to achieve a certain ‘score’, or they may experience heightened anxiety about their sleep quality.

This can worsen sleep and insomnia symptoms.

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Just like how obsessing over our body weight by checking the scales every day doesn’t help us lose weight, obsessing about our sleep tracker data won’t actually improve our sleep problems.

And it’s important to consider how sleep tracking data influences our perception of sleep quality.

In a 2018 study, participants with insomnia were given fake sleep tracker feedback. Those who were told they slept poorly reported impaired daytime functioning along with increased sleepiness and fatigue compared to those who were told they slept well, regardless of how they’d actually slept.

But I just want to stop feeling tired all the time

If you're struggling with insomnia (problems falling or staying asleep despite allowing adequate time for sleep), make sure you seek professional healthcare from a GP, sleep physician or sleep psychologist, and speak to them about evidence-based treatments like Cognitive Behavioural Therapy for Insomnia (CBT-I).

A tired barrista at a coffee shop — Let how you feel during the day be your guide, even if the data suggests a poor night's sleep. Picture: Getty Images

CBT-I is one of the most effective treatments for managing and improving insomnia symptoms, with techniques that address sleep-related anxiety, improve your sleep drive and regulate your circadian rhythms.

Check out the Sleep Health Foundation’s Insomnia Fact Sheet to learn more about insomnia and effective treatment options. The Sleep Health Foundation has links to free and effective online CBT-I programs like This Way Up Managing Insomnia.

And if your sleep tracking score is good, but you still feel tired or sleepy during the day, it could be that you have a higher sleep need. Try sleeping for nine to 10 hours then comparing how you feel during the day.

Or you could have a sleep condition like Obstructive Sleep Apnoea or Restless Legs Syndrome that can interfere with your sleep quality, or Hypersomnia, which makes you feel sleepy and tired no matter how much sleep you get.

The best sleep tracker is already built into all of us

Rather than obsessing over daily scores, also consider your personal perception of sleep: let how you feel during the day be your guide, even if the data suggests a poor night's sleep.

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Ask yourself: Am I tired or sleepy throughout the day? Do I feel good, physically and mentally? Do I need lots of caffeine to get through my day?

Try not to evaluate how well you slept based on how you feel immediately after you wake up, because many of us feel groggy or experience sleep inertia for a few hours.

Sleep is important, and sleep tracking has become a popular way to gain insights into our sleep. When used as a general guide, sleep trackers can be really helpful for establishing good sleep-wake routines and focusing on your health and wellbeing.

But if you become anxious about your sleep or are still feeling sleepy despite OK sleep tracking data, it may be time to stop tracking and see a healthcare provider like a sleep physician or sleep psychologist to get your sleep checked out.

This article was first published on Pursuit. Read the original article.

Prof

Amy Jordan

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Melbourne School of Psychological Sciences

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Faculty of Medicine, Dentistry and Health Sciences

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Sleep

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