My PhD supervisor Antonio García-Bellido used to say that one should “sleep with the problem”, and I give the same advice. Science is a creative activity and an amount of obsession is essential for scientific progress. I tell my students that scientific topics are not interesting or boring; it is scientists who make them interesting by finding unexpected sides of the issue or establishing unsuspected connections with other processes. It is there where their creativity lies. Curr. Biol. 16: R976-977.