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Parent is suggesting that sleeping must be good on the macro level. That does imply that it must also be good for the animal, right? In order to statistically benefit the population, the benefits to any given animal must statistically outweigh the costs. It can’t be all bad for all animals and still be good for the whole.

But sleep can be partially bad for some animals, they can be more prone to becoming prey while sleeping (though Google tells me sleep also prevents nighttime activity where predators have the advantage). There are definitely evolutionary adaptations around sleep to make it safer, sleeping in trees, sleep patterns & duration, hypnic jerk, etc.

Not only that, there are 'parasitic genes' that are wholly bad for the animal and the species.

I don't know why this is downvoted. It's entirely feasible that weaknesses in a species (or its individuals) may be beneficial for the ecosystem and hence survival of the species in the long term.

E.g. rabbit population being culled by predators may prevent the rabbits from eating their feed plants to extinction.