Why does MBSR ask for 45 minutes a day?

Because that was the length chosen when the programme was designed, not because a trial identified it as optimal. In interview material reproduced in a 2026 review, Jon Kabat-Zinn is quoted as saying that 45 minutes seemed long enough to settle into stillness and sustained attention, and describing the choice as a good intuition. Those words have not been verified against a primary text by Kabat-Zinn himself, so they are reported here at one remove. MBSR has strong clinical evidence as a complete package, but that evidence supports the programme, not the necessity of each individual minute. Participants in MBSR and MBCT trials complete around 64% of assigned home practice on average, so the dose that produced those results was in practice shorter than the prescription.