We have long understood that sleep is essential for the human body, but the precise functions of sleep remained elusive for many years. Recent scientific research has begun to unravel the mysteries of what happens in the brain during sleep and how these processes can be harnessed to solve problems and enhance creativity.
One of the most intriguing aspects of sleep is its role in memory consolidation and problem-solving. According to the active systems consolidation theory, our brains replay old memories while we sleep, stabilizing and strengthening them. This process not only protects memories from interference but also integrates new information into our existing memory network.
Memory and Problem-Solving
Research has shown that sleep plays a significant role in forming long-term memories and assists with problem-solving. A 2018 study suggested that the synergy between REM and non-REM sleep phases allows for more creative problem-solving solutions. Although initially theoretical, this idea has gained support from subsequent studies.
For instance, a 2021 study tested participants using a problem-solving video game. Participants either stayed awake or slept before attempting to solve a new puzzle. The study found that 62% of participants who slept solved the problem, compared to only 24% of those who remained awake.
“This memory reactivation during sleep is assumed to have a two-fold function, on the one hand stabilizing and strengthening initially labile memory to representations making them less susceptible [to] interference, and on the other hand reorganizing and integrating new memories into the pre-existing network of long-term memories in a process of system consolidation,” explains a 2021 paper.
This finding aligns with a 2019 study that demonstrated the possibility of “hacking” the brain’s problem-solving function. Participants were exposed to puzzles with associated sounds, and during sleep, sounds linked to unsolved puzzles were played. In the morning, participants showed greater success in solving these puzzles.
“We know that people rehearse or ‘consolidate’ memories during sleep, strengthening and reorganizing them. It’s also known that this natural process can be boosted by playing sounds associated with the information being rehearsed,” said first author Kristin Sanders.
However, as senior author Mark Beeman cautioned, sleep aids problem-solving when we have all the necessary pieces, but it won’t magically provide solutions to complex problems beyond our understanding.
Decision-Making and Sleep
Beyond problem-solving, sleep also influences decision-making. A 2024 study from Duke University found that sleeping on a decision helps avoid primacy bias, where initial information unduly influences our choices. This can be particularly beneficial for complex decisions, as sleep provides the distance needed for more rational choices.
“Sleep allowed them to make more rational choices,” noted lead author Allie Sinclair.
While not practical for every decision—such as choosing a lunch option—sleep can be a valuable tool for more significant choices.
The Power of Dreams
Dreams, particularly during hypnagogia—the state between wakefulness and sleep—may also play a role in problem-solving. Inventor Thomas Edison reportedly used a technique known as the “spoon test” to tap into this creative state. By holding an object that would fall and wake him as he drifted off, Edison claimed to enhance his creative thinking.
In 2021, French scientists tested this claim, finding that sleep onset is indeed a “creative sweet spot.” Participants faced with a math problem containing a hidden rule showed greater success in solving it after a brief nap, compared to those who stayed awake or fell into a deeper sleep.
“So it turns out that Edison was right, sleep onset really is a creative sweet spot, and sleeping on it works,” writes Dan Denis, a psychologist at the University of York.
While not applicable in all scenarios, such as during a driving test, the findings highlight the potential of sleep to enhance creativity and problem-solving.
Implications and Future Research
The growing body of research underscores the importance of sleep in cognitive functions, particularly in memory consolidation, problem-solving, and decision-making. As scientists continue to explore these mechanisms, the potential applications of sleep in educational and professional settings are vast.
Future research may further uncover how to optimize sleep for cognitive benefits and explore the limits of sleep’s problem-solving capabilities. As we deepen our understanding, the age-old advice to “sleep on it” may become a scientifically endorsed strategy for tackling life’s challenges.
