Placebo EffectMental HealingPlacebosSuggestionAcupuncture TherapyDouble-Blind MethodCardiovascular Physiological ProcessesClinical Trials as TopicHypnosisAnalgesiaAcupunctureRandomized Controlled Trials as TopicControlled Clinical Trials as TopicPainTreatment OutcomeIrritable Bowel SyndromeResearch DesignCross-Over StudiesPain MeasurementSingle-Blind MethodPain Management