When a problem won’t yield an answer, sleep might offer more than just rest.

Axar.az reports, in a controlled laboratory experiment, researchers found that playing sounds linked to unsolved puzzles during REM sleep increased the chances that sleepers would dream about those problems, and in some cases, solve them the following day.

The study, published in Neuroscience of Consciousness, involved 20 participants, many of them experienced lucid dreamers. Before going to bed, they were asked to solve a series of puzzles designed to require creative thinking. Some puzzles remained unsolved. Each one was paired with a distinct sound, such as a short piece of music, to create a mental association.

While participants slept, researchers monitored their brain activity and waited for REM sleep, the stage most closely associated with vivid dreaming. During this phase, selected sounds linked to the unsolved puzzles were played quietly. Participants had been instructed in advance to continue working on any puzzle if it appeared in their dreams.

According to the results, the sound cues increased the likelihood that specific puzzles would appear in dreams. Participants reported dreams involving the puzzles or related ideas, and some even signaled during sleep that they were actively engaging with the task. Overall, a portion of the unsolved problems was revisited during the night.

When tested again the next morning, puzzles that had been incorporated into dreams were more likely to be solved than those that had not. However, simply hearing the sound during sleep did not appear to improve performance unless the puzzle itself became part of the dream. Differences between cued and uncued puzzles were present but not consistently strong across all participants.

The study also found variation between lucid and non-lucid dreams. While lucid dreamers were able to intentionally engage with the tasks in some cases, successful outcomes were not limited to those experiences.

The findings suggest that it is possible to influence dream content using external cues and that dreaming about a problem may contribute to solving it later. Researchers note that while the effects are modest, the results provide experimental evidence linking REM sleep dreaming with problem-solving performance.