Saturday, January 19, 2008

Fish Insomnia

Scientists report that some members of a common species of aquarium fish, Zebra Danios, have a genetic mutation that causes them to sleep 30% less than their normal brothers and sisters. The scientists call it a case of fish insomnia. But unlike human sufferers of narcolepsy, who lack the same neurotransmitter these insomniac fish lack (hypocretin), the zebrafish don't appear to be impaired during the day from lack of sleep.

The fish did not flop over. They were no sleepier during the day, and they were evening insomniacs.

Zebrafish are no slouches when it comes to learning. With training, Zebrafish can learn to avoid a net quite well - as aquarium hobbyists have known for a long time!

No word yet if lack of sleep impairs the ability of zebrafish to learn, as the evidence shows that it does in people. Sleep appears important for learning and brain plasticity in virtually all living creatures, including worms! Paradoxically though, several recent studies show that another sleep-inducing neurotransmitter, melatonin, actually impairs learning and memory formation in both zebrafish and in mice.

It goes to show that sleep and learning are very complicated. Scientists are learning a lot from our little friends.


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