Wearable sleep trackers: Are they any good?

The rise in association of lack of sleep and various disorders has increased the priority for good quality sleep. With a boom in the sale of activity trackers in the past few years, the number of people tracking their daily activities such as walking, running and exercises has increased multifold. Sleep tracking wearables have now been added to this list. 

These devices track our sleep patterns and give us information about when we are sleeping, how many hours we are sleeping, the quality of sleep and some devices even calculate the different stages of sleep. But how accurate are these sleep wearables? Are they effective? Are they helping us or creating new problems?

How do wearable sleep trackers work?

Sleep wearables like watches or rings give us information about our sleep patterns. “Parameters like body movements and heart rate are tracked to give us a sleep score. 

The score can be 50-100 based on these parameters,” said Dr Sunil Kumar K, Lead & Sr. Consultant – Interventional Pulmonology, Sleep Medicine and Transplant Physician, Aster CMI Hospital, Bengaluru.

In a hospital, sleep is tracked by a procedure known as polysomnography. Different parameters including stages of sleep, brain activity, heart rate, body temperature, airflow and oxygen saturation are measured during this procedure.

“Sleep wearables like watches or rings utilise sensors and remote detecting technologies to capture signals. The most common signals captured are motion [through accelerometer] and heart rate [through photoplethysmography],” says Jesse Cook, MS, sleep scientist and clinical psychology scholar at University of Wisconsin.

“Devices will vary in their feedback parameters. Devices track different parameters like time spent in the bed trying to sleep, time spent sleeping, sleep efficiency etc. These signals are analysed to provide feedback related to sleep characteristics in the night and overall sleep habits and patterns,” Cook explains. 

How accurate are sleep trackers?

“Modern sleep trackers have evolved to appropriately characterise the stages of sleep around 50-70% of the time. The technology has improved greatly since the origin of sleep trackers, but problems exist with the accuracy of calculating a few parameters such as motionless wake [being awake without moving]. This leads to overestimating sleep ability and quality,” says Cook.

Dr John Kruse, Neuroscientist, Psychiatrist based in San Francisco, USA said, “The gold standard for sleep studies traditionally uses EEGs (Electron Encephalogram), EMGs (Electromyography), devices to measure nose/mouth, chest expansion and sometimes sound recordings. However, the readily available sleep trackers use devices that are only in the accuracy range of 70 – 90% to reliably assess sleep stages.” 

Effects of sleep trackers on individuals

A counsellor Mumtaj Begam, Fortis hospital, Chennai says that sleep trackers can have adverse effects on individuals. “Any error or miscalculation would affect the user’s sleeping patterns and lifestyle decisions”, said Begum. 

• Anxiety – Low sleep scores can create unusual anxiety, depression and negative self-image.
• Self-diagnosis – In the case of improper sleep patterns, users tend to self-diagnose as insomniacs or with other sleep disorders without a physician’s consultation
• Addiction – Users tend to rely on gadgets to get better sleep scores than their body clock.
• Variable sleeping patterns – Everyone has a different sleeping pattern. Some might feel refreshed after 6 hours of sleep and some might need 9 hours. As their sleep scores do not consider this aspect, they are left wondering why they have low scores when they slept well.

Takeaways

If used correctly, a wearable sleep tracker can help us identify our sleep patterns, assist in making lifestyle changes for a better sleep and therefore improve our health. According to Dr. Pankaj Anand, Senior Consultant, Critical Care & Internal Medicine, Fortis Escorts Hospital, Jaipur:

• Sleep trackers are not the gold standard for sleep assessment. Rather they are tools that can give feedback on your sleep patterns, which can assist you in making right lifestyle decisions for better sleep and better health.
• One shouldn’t fixate on sleep scores and get distressed because of it. Rather take it as a crude measure of sleep stages and use it to detect changes over time in one’s sleep. If they are making you anxious, they are almost certainly more of a hindrance than a help.