Complex decisions are best left to your unconscious mind to work out, according to a new study, and over-thinking a problem could lead to expensive mistakes.

The research suggests the conscious mind should be trusted only with simple decisions, such as selecting a brand of oven glove. Sleeping on a big decision, such as buying a car or house, is more likely to produce a result people remain happy with than consciously weighing up the pros and cons of the problem, the researchers say.

Thinking hard about a complex decision that rests on multiple factors appears to bamboozle the conscious mind so that people only consider a subset of information, which they weight inappropriately, resulting in an unsatisfactory choice. In contrast, the unconscious mind appears able to ponder over all the information and produce a decision that most people remain satisfied with