Author Iain M. Banks presented readers with a diversity of transhuman and extraterrestrial characters in his Culture novels, including a paranoid spaceship captain named Kraiklyn with the augmented power of unihemispheric sleep.
We have a name for this in the real-world: unihemispheric slow-wave sleep. Marine mammals like the bottlenose dolphin and the Beluga whale employ the same strategy so that there's always a waking brain half to surface and breathe.
You might think only humans in post-scarcity sci-fi novels would have a chance at this ability, but you'd be wrong: You employ a version of this sleep-with-one-eye-open strategy every time you sleep your first night in a new location.
In a study published in the journal Current Biology, Brown University researchers investigated the "first-night effect" by monitoring the brain activity of 35 volunteers during two nights of slumber. Like a team of adventurers encamped in a fantasy novel, one network of brain regions stayed awake the whole first night to watch out for orc attacks: the default-mode network of the brain's left hemisphere.
It makes perfect sense, right? We experience the rumblings of the default mode network as a constant background static of worry and anxiety over past embarrassments and future threats. Who better to stare out into the dark and fret about orcs? Yet the study volunteers didn't exhibit heightened states of anxiety, so perhaps a weird Airbnb venue is exactly what that brain network needs to keep from chewing on itself.
The researchers believe these findings to be the first of their kind, so we're just getting started here. They only looked at four networks in the brain, so they're not sure if the left hemisphere is the lone watchman, or if it swaps out duties with the right. And if so, why does the default-mode network pull first watch?
However it shakes out, our unihemispheric sleep powers fall far short of old spacefaring, transhuman Kraiklin. Don't try and get the jump on him, especially if you're all groggy from that first night aboard his ship.