Dr. Guy Leschziner, a prominent neurologist and consultant in London's sleep-medicine arena, has recently indicated his belief that sleep-tracking apps and similar technology may backfire on the user. This is apparently due to a 'one-size-fits-all' approach to sleep metrics employed by these apps.
https://www.notebookcheck.net/Sleep-tracking-tech-may-not-fit-purpose-yet-accoding-to-leading-neurologist.423648.0.html