Is your watch keeping you up? What sleep trackers get right, and what to take with a grain of salt.
Seven and a half hours of sleep, a clear head, and then the watch reads: Not enough REM. If you've ever started your day doubting how you feel because of a number on your wrist, you're not alone. Our team of osteopaths at Prom Health have been there too.
Sleep trackers are everywhere now, and they can be genuinely useful. But they're better at some things than others, and for some people, checking the data each morning can become a source of worry in itself.
At the Sports Medicine Australia (SMA) and ACSEP Conference in Brisbane last week, Professor Shona Halson from the Australian Catholic University's SPRINT Research Centre shared what the research says about wearables and sleep. Here's what we took home, and what it means for you.
What your watch is pretty good at
Modern wearables are good at telling whether you're asleep or awake. In a 2024 study comparing three popular devices with a full laboratory sleep study, all three picked up sleep correctly at least 95% of the time, and estimated total sleep time similarly to the lab test in healthy adults (Robbins et al., 2024).
That makes your watch a reasonable guide to:
How long you slept
When you went to bed and woke up
How regular your sleep is from one night to the next
The last one matters more than many people realise. A 2025 American Heart Association statement on sleep health highlights regularity as its own part of healthy sleep, with more consistent sleep-wake timing linked to lower cardiovascular risk in large studies (St-Onge et al., 2025). The conference notes went a step further: in people with chronic health conditions, consistency may matter even more than total hours.
What to take with a grain of salt
Sleep stages (light, deep and REM). In a sleep lab, stages are measured with polysomnography. Sensors record brain activity (EEG), eye movements (EOG) and muscle activity (EMG) through the night. Your watch has none of these. It estimates your stages from movement and heart rate. Accuracy for staging varies a lot between devices and studies, from about 50% to 86% depending on the stage and device (Robbins et al., 2024; Lee et al., 2023), and some devices over- or under-count deep and light sleep by 40 minutes or more (Robbins et al., 2024). So a night of "not enough REM" may simply be the algorithm's best guess.
Sleep, readiness and recovery scores. These are each brand's own formula, and they're not standardised or published. Most lean heavily on how long you slept, and some blend in heart rate, heart rate variability (HRV) and "stress" readings. Overnight HRV in particular responds to almost everything you did that day: a hard training session, a late meal, a couple of drinks or a stressful afternoon. That can make it useful for spotting your own patterns over time, but it isn't a verdict on how well you slept.
Look at the trend, not the night
Even great sleepers have bad nights. One poor score tells you very little. A run of short or irregular nights over a week or two tells you much more.
There's also a name for getting stuck on the numbers: orthosomnia, a preoccupation with "perfect" sleep data. Worry about your score can make it harder to switch off at night, which is the opposite of what the tracker is meant to help with. Depending on how strictly it's defined, a 2024 general population study estimated it affects roughly 3% to 14% of people (Jahrami et al., 2024). If checking your data leaves you anxious, try putting the watch away for a week and noticing how you actually feel.
These are the benchmarks commonly used for healthy adults, from the table Prof Halson presented (St-Onge et al., 2025):
What to look at | Healthy adult benchmark |
Total sleep | 7 to 9 hours a night |
Time to fall asleep | Within 30 minutes |
Time awake overnight | Less than 30 minutes in total |
Regularity | Bed and wake times vary by less than about an hour, day to day |
Sleep stage percentages also appear in research tables, but because your watch estimates stages, they're the least useful numbers to chase.
Why it's still worth paying attention to sleep
None of this means sleep doesn't matter. It matters a lot, which is exactly why the useful numbers are worth knowing.
A 2025 umbrella review, which pooled the findings of many earlier systematic reviews, found that regularly sleeping less than seven hours is associated with:
higher risk of high blood pressure, stroke and coronary heart disease
higher risk of obesity and type 2 diabetes
harder-to-manage emotions, more anxiety and more negative reactions to stress
a higher risk of early death overall (Shah et al., 2025)
A US survey of more than 138,000 adults likewise linked ongoing sleep disturbance with obesity, diabetes, heart attack, stroke and coronary heart disease (Grandner et al., 2012). On a day-to-day level, tiredness also tends to mean more snacking on calorie-dense food and less movement. These are associations from population studies, not a prediction for any one person. But they're a good reason not to accept ongoing poor sleep as normal.
So after a single rough night? Go easy on yourself. Adjust your plans where you can, and save the big decisions for a better-slept day.
Tips for better sleep
1. Keep a regular wake-up time, weekends included. Wake time is the easiest anchor to control, and a steady wake time tends to pull your bedtime into line. Aim for bed and wake times that vary by less than about an hour from day to day.
2. Move most days. A large meta-analysis of 66 studies found that regular exercise helps people fall asleep a little faster, sleep slightly longer and moderately improves how well they rate their sleep. Aerobic and resistance-type exercise worked similarly well (Kredlow et al., 2015). More recent reviews comparing exercise types found Pilates, yoga and aerobic exercise among the most helpful for sleep quality (Xie et al., 2024; Wang et al., 2025). Walking counts too. Choose something you enjoy enough to keep doing.
3. Use your data gently. Check the weekly trend rather than each night's score, and take a break from tracking if it's adding to your stress.
4. Don't put up with aches that keep you awake. Pain that wakes you or stops you getting comfortable is worth having looked at. That's where our team can help you out, stiff hips, a tight back or neck. Our osteopaths can assess the area and treat any relevant restrictions.
When to get help
A wearable can't diagnose a sleep problem. See your GP if you:
snore loudly, or someone has noticed you stop breathing or gasp in your sleep.
feel tired or sleepy most days, even after what should be enough sleep.
regularly struggle to fall asleep or stay asleep for weeks at a time.
For ongoing insomnia, sleep guidelines recommend cognitive behavioural therapy for insomnia (CBT-I) as the first treatment to try, ahead of sleeping tablets (Riemann et al., 2023). It's a structured program, usually over several weeks, that works on the habits and thoughts that keep poor sleep going. Your GP can talk you through options, including online programs.
We all know the difference a few good nights' sleep can make to how we feel and function. So try a few of these tips, keep an eye on the trend rather than the nightly score, and above all, notice how you feel.
Thanks to Prof Shona Halson (ACU) and Sports Medicine Australia for the insights shared at the 2026 SMA and ACSEP Conference. This article is general information only and isn't a substitute for advice about your own health.
References
Grandner MA, Jackson NJ, Pak VM, Gehrman PR. (2012). Sleep disturbance is associated with cardiovascular and metabolic disorders. Journal of Sleep Research, 21(4), 427–433.
Jahrami H, Trabelsi K, Husain W, et al. (2024). Prevalence of orthosomnia in a general population sample: a cross-sectional study. Brain Sciences, 14(11), 1123.
Kredlow MA, Capozzoli MC, Hearon BA, Calkins AW, Otto MW. (2015). The effects of physical activity on sleep: a meta-analytic review. Journal of Behavioral Medicine, 38(3), 427–449.
Lee T, Cho Y, Cha KS, et al. (2023). Accuracy of 11 wearable, nearable, and airable consumer sleep trackers: prospective multicenter validation study. JMIR mHealth and uHealth, 11, e50983.
Riemann D, Espie CA, Altena E, et al. (2023). The European Insomnia Guideline: an update on the diagnosis and treatment of insomnia 2023. Journal of Sleep Research, 32(6), e14035.
Robbins R, Weaver MD, Sullivan JP, et al. (2024). Accuracy of three commercial wearable devices for sleep tracking in healthy adults. Sensors, 24(20), 6532.
Shah AS, Pant MR, Bommasamudram T, et al. (2025). Effects of sleep deprivation on physical and mental health outcomes: an umbrella review. American Journal of Lifestyle Medicine.
St-Onge MP, Aggarwal B, Fernandez-Mendoza J, et al. (2025). Multidimensional sleep health: definitions and implications for cardiometabolic health. A scientific statement from the American Heart Association. Circulation: Cardiovascular Quality and Outcomes.
Wang H, Xin X, Pan Y. (2025). The best approaches and doses of exercise for improving sleep quality: a network meta-analysis and dose-response relationship study. BMC Public Health, 25, 1371.
Xie W, Lu D, Liu S, Li J, Li R. (2024). The optimal exercise intervention for sleep quality in adults: a systematic review and network meta-analysis. Preventive Medicine, 183, 107955.
