Sound cues in dreams double problem-solving success, study finds

Sound cues boost puzzle solving

Northwestern University researchers used sound cues to trigger dreams about specific puzzles, doubling the rate at which participants solved those problems the next morning. The study utilized a technique called targeted memory reactivation (TMR) to influence subconscious thought during sleep. Lead author Karen Konkoly and her team at the Paller Cognitive Neuroscience Laboratory published the findings after testing 20 participants.

Researchers first assigned participants complex puzzles they could not solve while awake. The team played specific audio clips while the subjects attempted the tasks to create a mental association between the puzzle and the sound. Once the participants fell asleep, the researchers played those same sounds during the REM stage of sleep to prompt the brain to revisit the unsolved problems.

The data showed a significant improvement in problem-solving ability after the cued dreaming sessions. Out of the 20 participants, 12 reported dreams that incorporated the specific puzzles linked to the audio cues. The results suggest that the brain continues to work on logical tasks even when the conscious mind is offline.

The success rates for the puzzles demonstrated the following changes:

• Baseline solving rates for unsolved puzzles sat at 20 percent.
• Solving rates rose to 40 percent for participants who dreamed of the cued puzzles.
• The 100 percent increase in success suggests that "sleeping on it" has a measurable cognitive basis.
• Participants who did not dream of the puzzles saw no significant improvement in solving rates.

Lucidity is not a requirement

The team specifically recruited people with prior experience in lucid dreaming for the experiment. These individuals often have better control over their dream environments and can actively search for insights while asleep. However, the researchers found that participants did not need to be aware they were dreaming for the technique to work.

In one instance, a non-lucid dreamer reported asking a character in their dream for help with the puzzle. Konkoly noted that this demonstrates how the brain can follow external instructions and respond to environmental sounds without conscious awareness. This suggests that the subconscious remains receptive to external stimuli throughout the night, regardless of the dreamer's state of mind.

The study indicates that targeted incubation works even when the dreamer lacks control over the narrative. This opens the door for cognitive therapies or learning tools that do not require specialized training in dream control. It also implies that the brain can process complex instructions while the body remains in a deep state of rest.

Small sample size limits findings

The small sample size of 20 people means these results require further validation through larger trials. The researchers also acknowledged that they cannot yet distinguish between the inherent creativity of dreams and the influence of pre-sleep intentions. Participants knew the purpose of the study, which introduces the possibility of demand characteristics influencing the data.

The research team highlighted several caveats in their published paper regarding the study design. They noted that the current methodology does not allow them to isolate whether dreaming itself is the catalyst for creativity. It is possible that the benefit emerges only when combined with a strong pre-sleep intention to solve a specific problem.

Furthermore, the researchers identified the following limitations in their work:

• The inability to fully blind participants from the study's purpose.
• The specific nature of the puzzles may not translate to all types of creative problem solving.
• The reliance on self-reported dream content, which can be unreliable or incomplete.
• The high barrier to entry for participants who must be capable of sleeping in a laboratory setting.

Advertisers target the sleeping brain

The success of dream incubation raises questions about the future of advertising and corporate interference in sleep. In 2021, the Molson Coors Beverage Company launched an experimental campaign designed to influence the dreams of Super Bowl viewers. Because of exclusivity rules preventing them from buying national airtime, the company attempted to reach the subconscious of its customers instead.

The Coors Dream Project used a specialized website to deliver visual and audio stimuli before sleep. The campaign featured an eight-hour soundscape of waterfalls and mountain imagery designed to play while participants slept. Coors claimed that trial runs successfully led volunteers to dream about the brand and its "refreshing" imagery.

The technique, known as targeted dream incubation, shares similarities with the Northwestern study's methodology. While the Northwestern team focused on cognitive benefits, the Coors project demonstrated the commercial potential of sleep-time cues. This shift from clinical research to marketing tactics has sparked a debate among neuroscientists regarding the ethics of "dream hacking."

Protecting the subconscious from tech

Konkoly previously worked on research published in October 2025 regarding the efficacy of dream incubation. That study confirmed that TMR can successfully increase the incorporation of real-world memories into dreams. While these techniques currently require a participant's cooperation, the rise of internet-connected home devices creates new vulnerabilities for the average consumer.

Advertisers could theoretically use smart speakers or smartphones to play trigger sounds while users sleep. This would require hijacking a device or gaining permission through a seemingly harmless app that requests access to the microphone or speakers. If a user leaves a sleep-tracking app running, an advertiser could use that data to time audio cues for the REM stage of sleep.

The potential for unconscious persuasion represents a new frontier for privacy advocates. As the technology behind dream manipulation becomes more accessible, the boundary between the waking world and the subconscious continues to blur. For now, the most effective defense against dream-time product placement remains a simple hardware solution: muting the smartphone or disabling smart assistants before bed.