Mobile phone
06 August 2019
News Category: 
Patient and health stories

A Royal Melbourne Hospital Sleep Physician is recommending people with sleep disorders avoid using sleep tracking apps and devices as they have been proven to be inaccurate.

Dr Su Hii, a Respiratory & Sleep Physician, has said the inaccuracies of sleep trackers in smart watches and apps can cause heightened anxiety around quantity of sleep.

“We see the polysomnography sleep study (PSG) as the gold standard. In the PSG, we use an electroencephalogram (EEG) to know where the patient’s brainwaves are at, to see how accurate they are in comparison to the sleep tracking apps, and they’re not,” she said.

Dr Hii explained the reason why sleep tracking apps are often inaccurate because they work off accelerators, built-in devices in smartphones and wearable devices that track movement.

“When you’re in REM you’re not supposed to move, and when you’re in deep slow-wave sleep you can still move, so the technology picks up on those movements.”

“But if you’ve got a partner in the bed that moves around a lot, it won’t be accurate as it can pick up their movements. It depends on the bed, it depends on how close you have your mobile with you (if you are using an app) - there’s a lot of inaccuracies from that,” she said.

Research has also proven accelerator technology in smart devices inaccurate. A 2015 study published in the Journal of Clinical Sleep Medicine concluded that the parameters and sleep staging in the app Sleep Time for iPhones correlate poorly with sleep cycles shown in a PSG, with a 2012 study finding that a Fitbit sleep tracker can overestimate sleep by an average of 67 minutes.

Four out of 10 Australian adults experience some form of sleep disturbance, costing $66.3 billion to the economy in terms of loss of productivity and wellbeing.

While Dr Hii says it is great there is a renewed interest in sleep with the rise of health and wellness apps, she stresses that you shouldn’t take the results of sleep tracker apps seriously, and to see a doctor if your sleep is affecting your day-to-day life.

“We don’t focus on patients’ sleep tracker results. We can use them as an overall opening discussion point, but we need to educate them on the inaccuracy of that and we need to focus on their subjective feeling, not so much on the data provided.”

“There’s a lot of talk in the media that people need to get 7-8 hours’ sleep and it may not show up on their app, and they may not show any symptoms of a disorder, but they start to panic long-term health wise”

“They start saying things like ‘I’m not getting 7-8 hours’ sleep, I’m going to have a heart attack’ - there’s a lot of anxiety around that inaccuracy,” she said.

Media Contact

For more information about this story, contact Communications on (03) 9342 7000 or email