A Controlled Medical Study
Using Hemi-Sync® Audio Tapes During Surgery
From The Monroe Institute

Over the years we have received scores of anecdotal reports identifying various benefits received by individuals using the Hemi-Sync tapes in our Surgical Support Series. Reported benefits have included: lower but stable blood pressure; deep relaxation; slower, deeper breathing; less and sometimes no pain medication required; less anesthesia during surgery; quicker return to consciousness in the recovery room, and accelerated recuperation.

We are pleased to announce the results of a controlled medical study involving the use of Hemi-Sync during surgery. These results were published in Anaethesia, August 1999, 54, pages 769-773 in an article entitled "Hemispheric-synchronization during anaethesia: a double-blind randomized trial using audio tapes for intra-operative nociception control," copyright 1999, Blackwell Science Ltd.

The study investigated the possible benefits for patients listening to Hemi-Sync audio tapes while undergoing surgery under general anaesthesia at Queen Mary’s Hospital, Sidcup, UK. A total of 76 patients, ranging in age from 18-75, participated in the study. To determine the relative benefits for patients listening to Hemi-Sync sounds, two control groups were established for patients to listen to non-Hemi-Sync sounds.

These groups listened to classical music or blank tapes respectively. Patients were assigned one of three numbered (but unlabelled) tapes using a computer-generated random number table. Of the patients participating, 25 (15 men, 10 women) listened to Hemi-Sync tapes, 25 (9 men, 16 women) listened to classical music tapes, and 26 (9 men, 17 women) listened to blank tapes.

The results revealed that patients who listened to Hemi-Sync tapes required substantially less analgesia during surgery while no significant differences were found between the classical music group and the blank tape group. Following are excerpts from the article:

"In our study, we found that patients exposed to a Hemi-Sync audio tape whilst undergoing surgery under ‘light’ general anesthesia required significantly less analgesia with fentanyl when compared with patients listening to a blank tape or to classical music... Patients in the blank tape and classical music groups required on average 4.5 times as much fentanyl as the patients in the Hemi-Sync group. This difference remained significant when regression analysis was used to control for the effects of age and sex... On the basis of the preliminary findings of this pilot study, we believe that larger randomized studies are now required which utilize all the tapes in the Surgical Support Series."