To test this, the researchers split the study’s 49 participants into four groups: a sleep group with audio guidance, a sleep group without guidance, a non-sleep group with audio guidance and a non-sleep group without guidance. Those in the sleep group were allowed to nap between one and five minutes after entering the N1 stage before being woken up. Those receiving guidance were then told to think about a tree before the process was repeated – in total, it went on for 45 minutes.

Those who remained awake but had audio guidance also received the prompt about the tree but were simply told to ‘mind wander’ for seven minutes before writing down their ideas.

After the 45 minutes were over, all 49 participants were asked to write a story about a tree – and the difference was stark. Not only did both napping groups show increased creativity immediately after the exercise, but those who napped with audio guidance (or dream incubation) were 43% more creative than their fellow napping group, and 78% more creative than those who stayed awake with no guidance.

A daily nap has a surprising benefit that has nothing to do with your energy levels