Scientists from the Universität Hamburg who explored the potential relationship between sleep and inspiration have found a surprising correlation between deep sleep and so-called “eureka” moments, where elusive and sometimes transformative ideas suddenly become clear.
Previous scientific and anecdotal evidence has occasionally suggested the possible sleep-inspiration connection. However, this new effort is the first to find a potential link to sudden creative or intellectual insight during sleep by directly monitoring brain activity at different sleep stages.
When the ancient Greek tyrant Hiero II of Syracuse wanted to know if the craftsman he had charged with making a golden crown had replaced some of the gold he’d provided with silver, he turned to scientist, inventor, and mathematician Archimedes. According to an oft-disputed account, when Archimedes suddenly solved the problem by figuring out the concept of displacement as he sat in a bath and saw the water level rise, he leapt to his feet and ran naked through the streets of Syracuse, screaming, “Eureka, Eureka!”
Whether the story is true or not, that expression, which translates in English to “I have found [it],” has often come to represent the sudden and unexpected appearance of a solution to a previous, often seemingly unsolvable problem. Even the daily newsfeed used by most researchers to communicate their achievements to the world media is known as “Eureka Alert,” in tribute to the very concept of intellectual inspiration.
Scientists and philosophers have tried for millennia to decipher the genesis of so-called eureka moments, with mixed results. Still, some anecdotal evidence has connected meditation, hallucinogenic substances, and even extreme experiences to moments of inspiration. One behavior often noted by both scientific and creative thinkers that results in eureka moments is good old-fashioned deep sleep, even if it is brief.
“I think a lot of us have made the subjective experience of having important realizations after a short nap,” said study author Anika Löwe from the Universität Hamburg.
To explore this connection, Löwe and co-authors Marit Petzka, Maria Tzegka, and Nicolas Schuck set up a series of experiments designed to look for the brain mechanisms during deeper stages of sleep that may be at the genesis of such clarifying experiences. First, 90 study volunteers were asked to track a series of dots moving across a screen. Next, the volunteers were assigned a task involving responding to the dots on the screen on a keyboard. Notably, a “trick” that could make the assigned task easier was left out of the instructions given to each volunteer.
After completing a set of four trials each, each requiring them to complete the “dots” task, the volunteers were instructed to take a 20-minute nap. During these naps, the volunteers were each connected to an EEG, which allowed the research team to monitor the activity within their brains as they slept.
When nap time was over, the volunteers were once again tested. Although the majority of the volunteers (70.6%) figured out the trick, the research team noticed a correlation between sleep, the EEG data, and the number of people who seemingly experienced a eureka moment and figured the trick out.
For example, only 55.5% of the people who never fell asleep during the 20-minute nap time employed the trick during retesting. The people who successfully napped but whose EEG showed they only reached the lightest form of sleep, called N1, performed slightly better, with 63.6% employing the trick.
Perhaps the most critical correlations came from the study volunteers who experienced the deeper level of sleep, called N2. In those cases, the volunteers experienced the eureka moment, allowing them to employ the trick a staggering 85.7% of the time. Although people who didn’t take 20 minutes to at least try to nap were not included, the team says a previous experiment showed non-nappers figured out the same trick at a 49% rate. This finding appears to support the new study’s correlation between sleep and eureka moments.
In one unusual finding highlighted by the research team, the EEG patterns of the volunteers achieving N2 sleep during their naps showed a deeper spectral slope than the others, hinting at the physical mechanism underlying the sleeper’s “a-ha” moment. Lowe says that although scientists have only recently begun to consider the EEG spectral slope as a factor in cognitive processes that occur during sleep, their results seem to support the possible connection.
“I find the link between the spectral slope steepness during sleep, aha-moments after sleep, and the downregulation of weights, which we identified as crucial for aha-moments in our previous computational work, very exciting,” the researcher said.
The team says another unexpected result was the reaction to their findings. Löwe said the reaction to the correlation was particularly strong from creative people, whose careers and passions often explore and exist due to unexpected inspiration.
“What really struck me when telling people in my environment, particularly creatives, about these findings was how much they resonated with people,” the researcher said. “Many of them could relate to our results with a personal experience of having a (creative) breakthrough after a nap.”
Moving forward, the team says they hope to further explore the correlation between sleep and inspiration, with an emphasis on the possible connection between EEG spectral scope and eureka moments unearthed in their study.
“It’s really intriguing that a short period of sleep can help humans make connections they didn’t see before,” Schuck said. “The next big question is why this happens. We hope that our discovery that it may be linked to the EEG spectral slope is a good first lead.”
Christopher Plain is a Science Fiction and Fantasy novelist and Head Science Writer at The Debrief. Follow and connect with him on X, learn about his books at plainfiction.com, or email him directly at christopher@thedebrief.org.