It's a truth universally acknowledged yet little understood: Great epiphanies arrive in the shower.

There's an entire sub-Reddit dedicated to the effect. So why does this hot and steamy environment seem to brew such interesting thoughts?

For years now, scientists have been arguing over the so-called 'shower effect', and why it occurs. Now, two new experiments have helped clear up some of the foggiest findings.

The latest experiments were led by Zac Irving, who studies and teaches the philosophy of cognitive science at the University of Virginia, and they imply that unwavering concentration on a task may be the enemy of creativity.

Instead of mulling over a problem until it is solved, the findings suggest you're better off taking a break and partaking in a different task that is mildly engaging, such as showering. This environment may allow your mind to wander freely, without purpose or direction, albeit with some constraints.

As your thoughts drift about, researchers think you are more likely to come up with something clever.

An entirely boring task, on the other hand, doesn't seem to constrain your thoughts enough to generate creative ideas. You're more likely to get distracted or keep thinking about the original problem.

"Say you're stuck on a problem," Irving explains.

"What do you do? Probably not something mind-numbingly boring like watching paint dry. Instead, you do something to occupy yourself, like going for a walk, gardening, or taking a shower. All these activities are moderately engaging."

Historically, experiments on the shower effect have produced inconsistent results. Some studies have found an 'undemanding task' lets the brain wander and allows creativity to flow. But other studies have failed to replicate the findings.

Irving thinks that is because of flaws in experimental design. Many past studies have conflated mind wandering with boredom, when in reality, the generation of unusual ideas may require a subtle balance between free thinking and focused thinking.

"They weren't really measuring mind-wandering," argues Irving. "They were measuring how distracted the participants were."

A study in 2015, for instance, found that when a person has too many thoughts unrelated to a task, it can make creative inspiration harder to come by. In other words, at some point, unconstrained thoughts become unproductive.

What's more, many past experiments have employed different types of lab-based distraction tasks that don't translate well to the real world, like clicking numbers on a computer screen.

Irving and his colleagues designed two new experiments to make up for these limitations.

The first experiment was based on 222 participants, most of whom were female. In an initial trial, these participants were given 90 seconds to come up with as many alternative uses as they could for a 'brick' or a 'paperclip'.

Participants were then randomly assigned to one of two tasks. The first group was instructed to watch an engaging, three-minute-scene from When Harry Met Sally. The second group, meanwhile, watched a three-minute video of men folding laundry.

Following the video intermission, both groups were unexpectedly given an extra 45 seconds to add more ideas to their original task.

The creativity of their responses was scored by researchers based on the number of ideas they generated, and the novelty of the ideas, based on originality.

At the end, participants reported how much their mind wandered during the video segments.

Ultimately, the authors found that during the engaging video, mind wandering was positively associated with more creative responses.

The benefits of boredom, on the other hand, did not seem to be driven by mind wandering. After watching the laundry video, participants put forward fewer unusual ideas than the other group.

"Together," the authors conclude, "these results suggest that different kinds of thinking drive creative incubation during engaging and boring tasks. Whereas engaging tasks lead to productive mind wandering, boring tasks may be beneficial because they allow one to oscillate between periods of focused and unbounded though."

The second experiment repeated the first experiment among 118 participants, but this time, one half of the group was specifically told they would be returning to the original task after the video, while the other half was given only a 'vague' indication that this might occur.

Afterwards, participants reported how engaging they found the videos.

The results from the second experiment support the central findings from the first experiment. Namely, they suggest that mind wandering—or freely moving thought—facilitates the generation of novel ideas, "but only during a moderately engaging activity that places some constraints on thought."

Interestingly, when participants knew they had to return to the original task, they generated more ideas during the boring video but with lower creativity scores.

This suggests that they were still thinking of the original task during the laundry scene. The movie scene, on the other hand, was just distracting enough to allow participants the ability to make interesting connections between both tasks.

Further research is needed to explore the 'why' of the shower effect, but these new results give us a better idea of 'how' mildly engaging tasks, like showering, can help us generate creative thoughts in the real world.

The study was published in Psychology of Aesthetics, Creativity, and the Arts.