If, at day’s end, you find it a challenge to dial down the dimmer switch of consciousness for a good night’s rest, take a tip from a cutting edge sleep researcher. Heptuna is an Atlantic Bottlenose dolphin who’s been getting solid shut-eye for years by sleeping in a hammock.
The problem of how best to put our minds to rest is hardly a new one, but recent research linking poor sleep to a host of health problems including heart disease and early death (“Wisdom of the Sleepyheads,” Scientific American, Sept. 2013) shows it may be an increasingly important one.
Heptuna the dolphin ingeniously made a hammock from a rub-rope – a thick length of line suspended at the surface of the water, usually used by domesticated dolphins as a kind of scratching post.
Not a bad approach to bedding down for the night. Especially since Heptuna, like others of his species, needs to remain close to the surface throughout the night in order to breathe.
In dolphins, unlike humans, breathing is a voluntary rather than an autonomic function. Makes sense for an air-breathing mammal that earns most of its living through deep-diving fishing expeditions. But it causes an interesting problem when it comes time to tuck in for the night.
For a voluntary breather, shutting consciousness down completely for any extended length of time would be the equivalent of a death sentence. So evolution has endowed dolphins with the ability to rest one half of the brain at a time. That leaves the other half alert enough to make conscious decisions to breathe periodically throughout the night – and brings a whole new meaning to being half asleep.
The concept of true half sleep seems so alien to us humans that even trainers who work regularly with the animals are sometimes prone to misinterpret the nature of dolphin consciousness.
Once when Heptuna was involved in learning a new task, one of his trainers witnessed the dolphin take a behavioral step backwards. Rather than acknowledging the blunder as a normal stage in learning acquisition – absolutely as common in humans and other animals as it is in dolphins – the trainer attributed the mistake to another cause entirely.
“Sometimes,” the trainer said, “I get the feeling that I trained half of his brain while the other half was sleeping – and now the trained half is asleep, and the conscious half doesn’t know the task at all.”
At the time I heard it, I thought the statement ridiculous. And, just for the record, I’ll acknowledge the persistence of my own skepticism and confess that I still subscribe to the learning curve explanation of Heptuna’s behavioral misstep.
But . . .
A phenomenon known as local sleep has since been discovered.
Professors of psychiatry Giulio Tononi and Chiara Cirelli of the University of Wisconsin-Madison recently reported that actively scurrying rats can actually be sleeping small portions of their brains even while appearing fully awake.
This localized sleep, they say, is “basically indistinguishable from the off periods observed during slow-wave sleep.” Not only that, but they have found evidence of human local sleep as well – apparently used to rest parts of the brain that have become overly tired after bouts of intense learning. (“Perchance to Prune,” Scientific American, Aug. 2013)
If true, it could well be that I owe Heptuna’s trainer an apology. The skeptic in me isn’t sure yet, so what I plan to do is sleep on it. Think I’ll try that tonight with one eye open. It’s sounding more and more like that just might be possible.
Copyright © Seth Slater, 2013