Anapana/ Breath Meditation is just Preparatory stage for next step of-Mindfulness/ Insight(vipassana) meditation which is residential course.
Scientist study it
Doctors recommend it
Successful people use it
Ancient teachings confirm it
( It is Vipassana Meditation. )
Vipassana is non Judgemental, Choiceless, Neutral observation (Simple Witnessing) of the reality within oneself.