Inemuri is a very light sleep allowing a quick wake up to re-engage as necessary. You can practice inemuri anywhere, including in public, e.g., on public transportation. Should go without saying that you wouldn’t want to do this while driving, flying a plane, or performing surgery, among other activities 😬
I tried to have an inemuri today on my way home from Dallas, pulling over near Waco. Turned out an inemuri was not going to work, I was asleep very quickly.