Our newest book, ASK A SCIENCE TEACHER, released by Experiment Publishing, contains 80 new Questions and Answers concerning science and everyday life. Below is a new Q & A.

QUESTION:
Do fish sleep?
ANSWER:
Yes, fish do sleep. Although it can be tough to tell, since they don’t have eyelids that open and close, fish spend part of each day sleeping. You can tell when they’re sleeping in fish tanks: they sit at the bottom and don’t move, motionless except for minimal correcting motions with their fins to remain in position. They seem to be in a trance-like state of suspended animation. Scientists have recorded brain waves of fish. They show a distinct difference in the patterns between being awake and being asleep. To conduct your own test, you can drop food in the tank while your goldfish is sleeping; you will perhaps notice the fish takes longer to respond.
Fish sleep is a bit different than the sleep we humans enjoy. For most fish, it is a period of rest and reduced activity, not the deep REM brainwave activity occurring in humans.
Fish need the restorative nature of reduced activity and slower metabolism that comes with sleep. In that respect, they are the same as humans and most all others in the animal kingdom.
Researchers kept some zebra fish awake by repeatedly giving them a mild electric shock. They found the fish suffered from sleep deprivation and insomnia. These pestered fish tried to catch up on their lost sleep as soon as they were left undisturbed.
Fish sleep behavior varies widely. Some fish will wedge themselves in a spot in the coral or mud. Some build a little nest. The parrot fish secretes a mucus sleeping bag around itself. Other fish will change color slightly, taking on a duller color so they are less noticeable. Sharks have to keep moving because they need a steady flow of oxygen and water moving through their gills. The behavior of minnows drastically changes when they are trying to get some zzzzz’s. They are very active in schools during the time they are awake, but they scatter and stay motionless during rest periods.
What do you call a fish with no eyes? Fsh