Picture the ocean at midnight. Every human on land is snoring into a pillow. But down here? The fish are still swimming, eyes wide open, not a pillow in sight. So do they ever actually sleep? The surprising answer is yes — they just do it in the weirdest ways imaginable.

First, let's clear up the obvious question. Fish don't have eyelids, so they can't close their eyes. That's why a "sleeping" fish looks exactly like an awake fish that forgot what it was doing. No blanket, no yawn, no cozy little bed. Sleep for a fish doesn't look like our sleep at all.

So what IS sleep, really? Scientists say it's a resting state where an animal slows down, stops paying much attention to the world, and can be woken up. Notice that word: rest, not eyes-shut. Once you define it that way, fish absolutely qualify. They just rest with the lights on.

Here's the tell-tale sign. A resting fish goes still, its breathing slows, and it stops reacting to little things swimming by. Poke the water gently near a snoozing fish and it barely twitches — the same fish would have darted away in a flash while awake. That drowsy, slow-to-react moment is the fishy version of being fast asleep.

Different fish have different bedtime routines, and some are gloriously strange. Some just hover in place like tiny floating balloons. Others wedge themselves into a rock crack so the current doesn't carry them off while they doze. A few even burrow into the sand and pull it up like a gritty blanket.

Then there's the parrotfish, the true genius of undersea sleepwear. Each night it blows a bubble of clear slime completely around its own body — a see-through sleeping bag made of goo. Scientists think this snot-tent hides its smell from hungry night-swimmers. Gross? Yes. Effective? Also yes.

But not every fish gets to fully clock out. Some, like certain sharks and tunas, must keep water flowing over their gills to breathe, which means they can't just stop and float. So they cheat. They rest one part of their brain at a time while the rest keeps them cruising slowly forward. Half asleep, half awake, always moving.

There's one more twist. Baby fish sometimes swim nonstop for their first days of life, skipping sleep entirely until they've grown a bit — and some deep-sea fish live in darkness so total that day and night don't really mean anything to them. Their rest doesn't follow our clock at all. Sleep, it turns out, comes in far more flavors than one.

So yes — fish sleep. They just do it standing up, tucked in rock, buried in sand, zipped inside slime, or with half a brain on watch. Next time you drift off in your soft, dark, blanketed bed, spare a thought for the goldfish, resting quietly with its eyes wide open, staring dreamily at nothing at all.