What induction style is this and why was it so effective?

Hey,

I had a trance session last night and it involved an induction style I've never experienced before.

Essentially I was told to open my eyes every time I inhaled, and close them every time I exhaled. Within a few minutes I felt myself drifting while the hypnotist droned on.

How is this different from staring at a single spot on the ceiling and why was It noticeably more powerful?

Thank you for any insight!