Comment by jjk166

Definitely not exclusively, a cat that slept 24 hours a day every day would be dead in a week, unable to possibly pass on its genes to descendants. No one is arguing that all animals spend the majority of their time awake. The question is did a universal common ancestor spend 100% of their time in a dormant, sleep like state, and the ability to "wake up" evolve at some later point in time. The answer is no.