Based on a report by Neurosciencenews

Most people have been told to “sleep on it” before making a tough choice. A recent study from Duke University shows there is real science behind that advice. Quick decisions often lean heavily on first impressions, while decisions made after a night’s rest are more balanced and rational.

Researchers tested this idea through a simple garage sale experiment. Participants were shown boxes filled with a mix of low-value and high-value items. Every box had the same total worth, but the placement of valuable items differed, sometimes at the top, sometimes in the middle, or at the bottom.

Those asked to decide immediately were strongly influenced by what they saw first. If a box started with a valuable item, they assumed the whole box was better, even overestimating its total worth by about 10%. This bias, known as primacy bias, highlights how strongly first impressions can shape judgment.

Interestingly, participants who waited until the next day to make their choice showed very different behavior. They evaluated the boxes more evenly, giving equal weight to boxes with valuable items in the middle or at the end. In other words, sleeping on it reduced the power of first impressions.

The results suggest that memory processing during sleep plays an important role. Instead of holding onto the initial spark of excitement, the brain organizes the entire experience and weighs all the information more fairly. By morning, participants were less swayed by the order of what they had seen.

This has clear implications outside the lab. First impressions can be useful when speed matters, like skimming the start of a book or deciding whether to continue a movie. But for choices with longer-term stakes, such as hiring, relationships, or major purchases, delaying the decision allows for a clearer perspective.

The study also shows why people often regret hasty decisions. When judgment is based mostly on the first details noticed, it is easy to overlook equally important information that emerges later. Giving the brain time to process prevents that imbalance.

In professional and personal life, this means building in space for reflection. Whether it is a business deal or a personal commitment, waiting a day before finalizing a choice can help minimize bias and lead to better outcomes.

The takeaway is simple: quick impressions are not always wrong, but they should not carry the full weight of important decisions. Sleep strengthens the ability to integrate the bigger picture, making choices less impulsive and more thoughtful.