Cats sleep from 16-18 hours a day.
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Sloths do sleep a lot but not as much as cats and koalas induce drowsiness from the Eucalyptus they eat. Koalas seek out the best eucalyptus by the smell of concentrations of eucalyptus oils in the leaves. During some times of the year the leaves are at it most potent and koalas are known to fall out of the trees and lay unconscious with cough drop breath for hours after ingesting large quantities of leaves.
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No info on the sleeping habits of turtles.
I do not know where you get your information from but I have known since grade 3 that koalas sleep an average of about 21 hours a day.
Use Google search and it will confirm that fact. Cats do not even make the top ten list.