Deep sleep seems to lead to more eureka moments

Waking up a deep nap seems to make people better in creative problems.

In a new study, people were more likely to have a “Eureka” moment if they had recently entered the second stage of sleep – in which brain activity slows down and brief explosions of electrical activity called sleep pins occur – whether they were sleeping slightly or not at all.

The results suggest that a brief deep nap can trigger precious moments of insight, explains Anika Löwe at the Max Planck Institute for Human Development in Berlin.

“I think we are at the very beginning of discovering what is really going on during sleep that makes him so beneficial,” she says. “One possibility is that during deep sleep, our brain passes through what is relevant and what is not relevant, and therefore when we wake up, we have these moments of insight that come to the essentials of the problem.”

Previous studies have mainly revealed that NAPs can stimulate creativity and help people solve problems, but there is a disagreement on the most beneficial sleep stage. Several suggest that the lightest sleep stadium NO REM, N1 is ideal – an idea embraced by Thomas Edison, which would be used to taking a nap while holding steel balls that were loudly crashed to the ground and would wake it up if it was dried too deep in sleep. But other studies suggest that the deeper N2 stage – even lighter than slow wave sleep, N3 – triggers more innovation.

To investigate more, Löwe and his colleagues asked 90 people aged 18 to 35 and did not have a sleep disorder to use a keyboard to classify the movement of the hundreds of flashing points models quickly on a screen. The researchers did not inform participants that the colors of the points have gradually started to predict the right answer halfway through the task.

Fifteen participants spontaneously understood the shortcut during the first 25 minutes of the task. The other 75 were invited to lie down for a 20 -minute nap in a quiet and dark room, while connecting to EEG monitors who followed their brain activity.

After the nap, they tried the tasks again. This time, most participants understood the shortcut of colors, but the probability of a moment Eureka seemed to depend on the depth of the nap. Among the 68 participants whose EEG data allowed high quality readings, 85.7% of people who fell into a deep sleep of N2 discovered the shortcut, against only 63.6% of those who only reached the lighter N1 phase and only 55.5% of those who did not slip at all.

The study clearly shows that deeper sleep facilitates Eureka moments – at least for this particular task, explains Itamar Lerner at the University of Texas in San Antonio. “The type of task used is essential to know whether it is stimulated by sleep or not.”

Delphine Oudiette at the Paris Brain Institute notes that different tasks conceptions could explain why her team has found much more problem solving after sleep of N1. “Maybe the two sleep stages count, but for different types of cognitive process that we must isolate to better understand,” she said.

Björn Rasch at the University of Friborg, Switzerland, says the results clearly support the idea that a deeper sleep can support problem solving. Despite this, it warns that the design of the study makes it difficult to separate the cause of coincidence. Because the participants were not assigned to chance at the sleep stages or studied individually in different sleep scenarios, it is possible that those who have managed to fall asleep in an Ikea chair in a research laboratory simply occur to be those who “simply have higher insights in insight”, especially after a nap, he said.