DO FISH SLEEP

As strange as it may seem, the answer to 'Do fish sleep?' is YES , but it’s not sleep as we know it. Why? Because they don’t have eyelids to close, they sometimes do it during the day, they don’t show the characteristic brainwave patterns like REM sleep seen in humans, and some, including most sharks have to keep swimming in their sleep.

How do fish sleep?

But fishes do have a period of reduced activity and metabolism which seems to perform the same restorative functions as nocturnal sleep does in humans. Some are more obvious about it than others and actually rest on the bottom or in coral crevices, and parrotfish secrete a mucus 'sleeping bag ' around themselves before they go to sleep.

However as trance-like as they may be they are still alert to possible dangers.

If you get up quietly in the middle of the night you will find your goldfish in an almost trance- like state, hovering near the bottom of the tank making just the minimum correcting motions with its fins to maintain its position in the water column. If you put food in when they’re like this they take noticeably longer than usual to respond, as if they have trouble waking up.

So now you know - fish can sleep!

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DO FISH SLEEP
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