I whiteboard things after the third interruption. My coworkers know if they interrupt me while I'm whiteboarding things, they are going to get sucked into the thought, and their question is moot. (Unless it relates to food)

So yesterday, I started thinking about a thing.
Thought quite a bit.

Started jotting it down and lost half of what I thought.

Nobody interrupted me.
It was just me, switching from lying down and thinking to getting up and typing.
The same happens in case I am using a pen and paper to write instead.