Hyperfocus refers to the sensation of being glued to a specific task, train of thought or what-have-you and being unable to turn your focus away to something else (e.g. a different task you have to do). It’s basically the negatively-flipped version of the concept of “flow”, which also describes being immersed in a task to the exclusion of outside distractions, but is seen as a positive state instead. Hyperfocus is considered a symptom of various kinds of neurodivergence, including ADHD and autism.

As far as I know I do not have either of those conditions, but hyperfocus is absolutely something that affects me. For example, sometimes I will be unable to tear myself away from my computer to go to bed until like, 1:30am because I got “stuck” going down a Wikipedia rabbit hole and learning new interesting things. Alternatively I might be unable to pull myself up and start cooking dinner until relatively late, because I was in a “flow state” working on my novel and didn’t even notice getting hungry until suddenly I was ravenous. For me, the dividing line between (negative) “hyperfocus” and (positive) “flow state” is the way that hyperfocus conflicts with maintaining healthy habits and routines. Also, I generally consider “flow state” to refer to doing something “productive” (like novel work), while hyperfocus can be something pointless like that time I got sucked into doing four hours straight of geography quizzes.