While lockdowns and face masks may feel like a thing of the past, for many people, COVID-19 is still causing problems. Long COVID is when people still have symptoms like fatigue, brain fog, or breathlessness weeks or even months after getting sick.

But the symptoms of long COVID are not very well understood, and it’s not clear who is more likely to get long COVID.

A study published in September 2024 in The Lancet Digital Health aimed to find out more, using data from smartphones and wearable devices like Fitbits.

How were smartphones and/or wearables used in the study?

• People filled in surveys on a smartphone app. They shared information on their mental well-being and what COVID-19 symptoms they had.
• People also shared data from their Fitbits, such as their heart rate, how much they slept, and their step count.

What did the study find?

• Resting heart rates stayed higher than normal for up to four months after having COVID-19.
• Some people reported feeling more depressed and anxious for up to three months after getting COVID-19.
• Fatigue was the longest-lasting symptom after getting COVID-19. Some people still felt fatigued for more than 140 days.
• People who were more active before they got COVID-19 were less likely to get long COVID.

This study shows that smartphones and wearables could help track long-term illnesses, like long COVID. This could help researchers better understand the symptoms of these illnesses and allow doctors to use this information to treat patients better.

Physiological presentation and risk factors of long COVID in the UK using smartphones and wearable devices: a longitudinal, citizen science, case–control study

• Read the full paper

A study published in July 2024 explored how the quality and duration of sleep affected long-term health risks. Using data from Fitbit smartwatches, researchers tracked each participant’s sleep over an average of 4.5 years. They found that around seven hours of sleep per night was linked to the lowest risk of health issues. Getting more or less sleep raised the risk of conditions like high blood pressure and generalised anxiety disorder. The study also looked at different sleep stages; people who had more REM (Rapid Eye Movement) sleep had a lower risk of heart rhythm issues, including atrial fibrillation. The Fitbit data gave a detailed look at sleep cycles that would be difficult to measure otherwise. However, the study mostly included college-educated people, which means the findings may not apply to everyone equally. The researchers plan to address this in future work. This kind of research shows how smartwatches can help us better understand the connection between sleep and health, potentially improving recommendations on healthy sleeping habits.

• Read the full paper