The pandemic not only disrupted sleep but may have also triggered an uptick in the use of wearable tech. Sleep tracking was featured at the Cardiovascular Health Tech virtual conference 2022, sponsored by the Institute of Electrical and Electronics Engineers Engineering in Medicine & Biology Society technical committee on Cardiopulmonary Systems and Physiology-Based Engineering.
This news organization interviewed presenter Kelly Glazer Baron, PhD, MPH, DBSM, an associate professor at the University of Utah, Salt Lake City, and a clinical psychologist specializing in behavioral sleep medicine.
The interview has been edited for length and clarity.
Question: Are consumer sleep trackers mainly divided into “nearables” – things that you put at the side of the bed or under the pillow – vs. wearables?
Dr. Baron: There are so many different devices these days. There are things that you put under your mattress or pillow; there are bedside recording devices; then there are headbands, rings, wrist-worn, all kinds of things.
Q: At the conference, Philip de Chazal, PhD, (University of Sydney) described the evidence on sleep tracking smartphone apps as woeful. Would you agree with that?
A: Yes. I would agree if you’re looking at how accurate they are at recording sleep, particularly compared with what we would define as the gold standard, which is a sleep study wherein you have electrodes on the scalp and you’re measuring the electrical activity directly.
They are best at detecting when you get into the bed and when you get out. But even then, there isn’t good evidence that they do that accurately when there are two people in the bed.
Overall, they may give you a general gist of what’s happening in terms of time in and out of bed, but we’re doubtful on their recording ability to tell sleep from wake time.
Q: Are the wrist-worn devices better for sleep tracking?
A: They’re getting better. We’ve used wrist activity monitors in research for years. They use an accelerometer to measure movement, and then an algorithm determines whether an interval of time is called sleep or wake.
Recently, they’ve incorporated more sensors, such as heart rate, and they can more accurately decipher rapid eye movement (REM) sleep from non-REM. They’re still not as good as doing a full sleep study. But they’re getting closer.
Q: If asked how you slept, most of us think we can answer without needing to look at a smartphone, but maybe not. Can you explain “paradoxical insomnia”?
A: You can’t really know if you’re sleeping because if you know you’re asleep, then you can’t be asleep because it’s a state of unconsciousness. How people decide whether they had a good night’s sleep probably depends on a lot of things about how they feel when they wake up in the morning or if they remember being up in the night.
Quality of sleep is not really something that people can directly ascertain. There is a selection of people who feel awake all night but they actually are sleeping. They feel that their sleep quality is poor: They’re suffering; they have insomnia, but from the objective data, they are sleeping fine.