Dolphins Maintain Round-the-clock Visual Vigilance

[Achilles Tang]

Even when a dolphin sleeps, half of its brain remains conscious. Knowing this, biologists wondered whether dolphins tire of keeping an eye on things. Monitoring for physical signs of sleep deprivation, researchers tested dolphins' reactions to visual and sound stimuli over a five-day period, and found that the animals were as sharp after five days as they had been at the beginning.

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