If you use a fitness tracker or smartwatch from one of a few prominent manufacturers — Google, Samsung, or Xiaomi — you've ...

Fitbit began testing its Sleep Profile Animal feature in beta in 2021, but Samsung was the first to fully roll out a sleep ...

But the basis for the modern trend of fitness trackers describing defined sleep patterns as aligning with one of several specific animals is more recent. In his 2016 book The Power of When ...