The researchers completed several different studies and found that even without noticing a difference in visibility, if the lighting around them was dim, participants were likely to be more creative. The reasoning came from the subconscious feeling of being more free from constraints and triggers a risky, explorative processing style.

Furthermore, other experiment found that for times when you don’t have control over the lighting around you, you can just think about being in the dark and it could have an effect - priming the idea of darkness–such as by taking five minutes to describe an experience of literally being in the dark, and recalling how it felt–was sufficient to boost creativity.