The project brought together researchers, clinicians, technology partners and industry to better understand fatigue and sleep disturbances across different chronic diseases, and how these symptoms can be measured objectively using digital technologies.

One of the key learnings from the final results is that there is no single digital signature of fatigue. Some signals were remarkably consistent across disease groups, while others appeared to be disease-specific.

Across cohorts, worsening fatigue and sleep-related symptoms were associated with:

• Slower reaction times, reflecting changes in attention and alertness

• Disruptions in circadian rhythm

• More periods of wakefulness during sleep

At the same time, different diseases showed distinct physiological signatures. In immune-mediated inflammatory diseases, for example, lower physical activity was associated with increased daytime sleepiness. In neurodegenerative diseases, changes in heart rate patterns were associated with worsening fatigue.

Huntington's disease particularly stood out, showing a larger number of associations, including a relationship between Sit-to-Stand transitions and fatigue.

These findings highlight both the potential and the complexity of using digital measures to better understand symptoms such as fatigue in daily life.

For McRoberts, it has been a privilege to contribute our wearable sensor technology and expertise to this ambitious project and to work alongside so many excellent partners.

A great project to have been part of and, hopefully, a strong foundation for what comes next in digital health research.