Why ‘sleeping over it’ actually works

Woman sleeping peacefully on memory foam mattress

We have all had to make difficult decisions. While most objective decisions can be made logically, those that involve complex variables may need a slightly different approach. Common advice suggests that you ‘’sleep over it’’. While it may come across as postponing the immediacy (and accompanying stress) of decision making, studies [1] suggest that for high impact decisions, tapping into the subconscious might be key. For the trivial ones — such as what to make for dinner tomorrow night, or what party to go to this weekend — it’s not really necessary.


Maarten Bos of Radboud University and Amy Cuddy of Harvard Business School wrote in Harvard Business Review [1] that sometimes ‘focus’ thinking could be the problem. They say that when the mind is ‘distracted’ and not consciously fixated on a problem (for example during sleep), there is an underlying cognitive process that actively weighs the pros and cons of relevant decision attributes. The difference here is the absence of biases that accompany conscious thought. In subconscious thought, different variables are weighed more equally, thus aiding decision making.


An experiment [2] published in the Journal of Consumer Psychology re-instates this notion. In this study, participants were asked to choose between different cars. Some of the cars had positive but irrelevant features like cup holders, a sunroof, and other fluff accessories. Others had more important features, like excellent safety ratings and better mileage. Part of the group was asked to choose a car immediately, while others were given a task (to distract them) before decision making. In all experiments, the immediate decision makers chose cars with many but unimportant features, while the group that decided later showed a stronger preference for quality cars (those with better safety ratings, et cetera). This indicates that unconscious thought indeed evokes an automatic weighing process. Our unconscious minds can process large amounts of information as long as we give it time to do so.


As always, results out of studies like these must be taken with a grain of salt. The results may not generalise to different age groups or people with different backgrounds than those sampled for the experiment. Furthermore, unconscious thought is not always the mode to rely on when faced with most worldly decisions. But for certain kinds of decisions (the complex ones), ‘sleeping on it’ may be more helpful than spending minutes or hours of conscious thought on it. The brain makes good unconscious decisions, but only when we let it. [3] 


1. https://hbr.org/2011/05/a-counter-intuitive-approach-t

2. https://www.sciencedirect.com/science/article/pii/S1057740810001191

3. http://science.sciencemag.org/content/311/5763/1005

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