Researchers at the University of Surrey say digital health tools like apps and wearables may not live up to their claims.

They question how effective these technologies really are for managing serious conditions like cancer, diabetes, and heart disease.

Their review of 140 studies found many trials rely on tech-savvy users and self-reported data, raising doubts about wider use.

They also warn that by the time long studies finish, the technology is often already out of date.