What are the sleeping patterns like for animals with no access to direct sunlight?

From what I’ve found, what isn’t much and I maybe wrong on this so let me keep checking but some animals that live in caves or sea life at the bottom of the ocean don’t sleep.

What I also want to find out is what happens to my fish at night as they don’t seem to sleep as we know it but I’m guessing it’s more complex than that.

What I know about sleep patterns is usually the higher in the kingdom the more sleep an animal requires. Sleep typically leaves an animal very vulnerable. Lions sleep something like 20 hours a day, but not too many animals are going to try and screw with them, being the kings of the jungle. There also might be a relationship between how long animals live and how much they sleep. I have a feeling an insect doesn’t sleep much and also doesn’t live long. But, that is just a guess. In the depths of the oceans I don’t know if those animals sleep according to dark and light? Interesting question. On land parts of the world that have many hours of darkness part of the year have many hours of light the other part of the year.

I’ll be following to see the answers.