June 29, 2005—Caring for a newborn requires a lot of sleepless nights, as any new parent knows. But scientists now have found that for some whales and dolphins, taking care of baby means going without sleep not for hours or days, but an entire month.

In today's issue of the journal Nature, a team of researchers reports that newborn killer whales and bottlenose dolphins, as well as their mothers, go without any sleep for the first month after the calves are born. What's more, the animals don't appear to suffer any ill effects from the lack of sleep, staying alert and in motion 24 hours a day.

The researchers made the discovery after studying two female killer whales and four bottlenose dolphins, with their calves, in captivity after birth.

How the animals—members of the animal order known as cetaceans—can function so well without rest remains a mystery, the scientists say. But staying awake during those first crucial weeks has some clear benefits. Wakeful mothers can keep an eye open for predators, while the calves' constant motion allows them to keep warm until they build their first layer of insulating blubber.

—Blake de Pastino

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