Interviewer: You have shown that biofeedback, dietary changes, and adoption of proper sleep habits all succeed in curing insomnia  You go so far as to claim that, with rigorous adherence to the proper treatment, any case of insomnia is curable  Yet in fact some patients suffering from insomnia do not respond to treatment
Therapist: If patients do not respond to treatment, this just shows that they are not rigorous in adhering to their treatment
It precludes the possibility of disconfirming evidence.