How sleep tracking apps and gadgets can actually ruin your sleep

It is estimated that one in three people regularly complain about sleep. So it’s no surprise that people care more than ever about getting enough sleep. This burgeoning interest has seen an explosion of sleep trackers that measure the number of hours of sleep you get asleep each night.

While we sleep, we go through cycles of “deep”, “light” and “rapid eye movements” (REM) sleep. The “deep” part of our sleep is mainly what leaves us feeling refreshed the next day. Most sleep trackers are a watch worn on the wrist and work by monitoring your body movements while you sleep to determine how much time you have likely spent awake compared to falling asleep. Some devices also look at changes in heart rate during sleep to estimate how much time you spent in each sleep cycle.

Despite their popularity, only a few studies have examined the accuracy of sleep devices. So far, research has shown that, compared to polysomnography tests – which experts use to diagnose sleep disorders – sleep trackers are only accurate 78% of the time in identifying sleep versus sleep. awakening. This accuracy drops to around 38% when estimating the time it took participants to fall asleep.

Polysomnography tests are the most accurate because they track brain waves, heart rate, respiration, blood oxygen levels, and a person’s body and eye movements during sleep through attached electrodes. to the skin and scalp. Analyzing brain wave patterns is the only definitive way to know if a person is awake or asleep, and what stage of sleep they are in.

But since sleep trackers are worn on the wrist, they make their nighttime sleep estimates by measuring body movement and sometimes heart rate data. As we move frequently during all stages of sleep, movement provides little clue as to the stage of sleep we are in. Many sleep devices also fail to differentiate one stage of sleep from another based solely on movement.

Since many consumer sleep devices have not been compared with polysomnography tests, it is difficult to determine their rate of accuracy. Additionally, the algorithms companies use to make sleep predictions are unknown, making it difficult for scientists to determine whether the assumptions made by sleep devices are valid.

Studies also show that sleep devices are underperforming in people with insomnia. People with insomnia tend to stay very still in bed in an attempt to fall asleep. But because sleep trackers only measure movement, one study found that watches were unable to differentiate sleep from wakefulness in people with insomnia.

Watches that incorporate heart rate data tend to be slightly more accurate when measuring sleep duration because heart rate fluctuates during different stages of sleep. However, even in devices that track heart rate, many experts are still unsure of their accuracy due to the limited research on them and the differences between each device. For example, a study of heart rate sleep trackers showed that two consumer devices tended to underestimate the number of deep sleep carriers achieved by up to 46 minutes.

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Sleep anxiety

Ultimately, this leads to the question of whether knowing our sleep is actually beneficial to us. After all, one of the best ways to stay awake is to really try to fall asleep. It sounds counterintuitive, but we see it clinically in patients with chronic insomnia, for whom excessive sleep preoccupation causes anxiety and bad mood related to sleep loss – leading to additional insomnia. .

A study published by our research group has shown that this effect can be worsened by sleep vigils. Participants were given sleep watches and asked to complete measurements of mood, daytime thinking processes, and sleepiness at regular times throughout the day. However, the “sleep score” given by their watches has been manipulated to show increased or decreased quality of sleep. The amount and quality of sleep for participants in both groups was the same.

The study found that those who were told they had a bad night’s sleep exhibited lower moods, difficulty with daytime thinking processes, and increased sleepiness. Those who have been told they have had a good night have shown otherwise.

This shows us that the data from these sleep trackers can change your emotional state and concentration levels during the day, even if the readings are accurate. Since people who sleep poorly may be more likely to use sleep trackers, this could be a problem as it could worsen mental health issues.

While few studies have examined this link so far, one report pointed out that more patients are seeking treatment for perceived sleep difficulties as a result of sleep tracker feedback. Even when such complaints are refuted by a polysomnography test, watches continue to provide a source of sleep-related anxiety. Since studies have shown that overuse of wearable devices (such as those used during exercise) increases anxiety and depression for health, there are concerns that sleep devices may have a similar effect.

While sleep devices can be useful for those who generally sleep well but want to follow or establish a better routine, people with poor sleep or mental health issues may want to avoid them. But the best measure to measure the quality of your sleep is to see how you feel every day. If you’re tired and having trouble concentrating, going to bed a little earlier each night can help you feel more rested – no devices are needed.

This article by Matthew Reid, Postdoctoral Fellow, Sleep and Circadian Neuroscience, University of Oxford, is republished from The Conversation under a Creative Commons license. Read the original article.

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Published January 17, 2021 – 09:00 UTC