Entrainment is what happens when one rhythm falls into step with another. Two systems with their own rhythms, once they can influence each other, tend to synchronise — the textbook case is a row of pendulum clocks on the same wall drifting into time with one another. It happens in the body too: rhythms such as heartbeat, breath, and brain activity tend to align to a strong, steady rhythm in the environment around them.
If coherence is the state we are aiming for, entrainment is how we get there.
Rhythm the nervous system can follow. Our light and sound carry deliberate rhythmic signals — a pulse, a tempo, a frequency — that the nervous system can synchronise with and follow back into regulation. A body holding too much sympathetic charge is led, gently, back toward heart and breath in rhythm.
Guided, not imposed. We do not drive the body into a state. We offer a rhythm steady enough to follow, and the nervous system finds its own way down — the body knows the way, we help it get there. The signals are an invitation the body can take, not a force applied to it.
The specifics live in the research. Which rhythms and frequencies we use, and the evidence for their effects, belong to our research arm rather than to this definition.