Being without a brain would suck for all sorts of reasons. TV would be nonsensical. Music would be meaningless. Life would be even more pointless than usual. But hey, at least you’d be free from the exhausting confines of sleep, right? Wrong! A new study out of Kyushu University in Japan proposes that sleep came before brains, and therefore, even the brainless need it.
To come upon this conclusion, a team of international researchers filmed tiny, water-dwelling hydras, and found that, despite lacking central nervous systems, the fresh-water creatures displayed signs of a sleep-like state. The hydras demonstrated a four-hour cycle of active and sleep-like states, indicating that they’re very sleepy teeny organisms.
Even more convincing, hydras exposed to melatonin, a common sleep aid, entered their sleep-like state more often than others. And the inhibitory neurotransmitter GABA, another chemical linked to sleep activity, immensely increased how much the hydras slept.
The researchers were also successfully able to use vibrations and temperature changes as a means of waking hydras from their slumber (which, let the cute little hydras sleep, you sick bastards) and inducing signs of sleep deprivation, such as more sleep the following day.
When taken together, all of this evidence suggests that sleep-like mechanisms appear on the evolutionary timeline before development of the central nervous system, or the brain. This also confirms that sleep is essential for life whether you have a brain or not. “Cell proliferation decreased when we gave the hydras sleep deprivation, meaning hydras need sleep to grow up well,” lead researcher Taichi Itoh tells me. “This can be seen in humans as well. For example, children need sleep not only for developing their brain functions, but also body growth. Thus, not only the system of sleep, but also even one of the purposes of sleep originates from before the animals acquired a brain.”
The implications of this study could be far-reaching and may impact our fundamental understanding of sleep, but Itoh says there’s more work to be done. “The mechanisms of hydra sleep regulation definitely contain the core idea of sleep itself,” he explains. “In other words, we might even be able to elucidate the ‘mystery of sleep’ using hydras, which is for sure one of the simplest animals. To speak of extremes, it may be easier to find the core system of sleep using hydras than animals with brains. That is so challenging, but we are going to try.”
Whatever they discover down the road, the message for now seems clear: Sleep, you can’t escape it. I guess I’ll take my brain off Craigslist then.