"Sham" procedure in this experiment may be not "real" placebo. Mikhail Glibitsky, ZRO KVANT 11 January 2011 If acupoints were illuminated by visible light (red LED) both in "laser" and "sham" experiments, this may question the results of the experiments. It is well known that red light can be used to influence the acupoints. Looking on Fig. 1, one can see that the skin is illuminated by visible light. If this was true during the experiments, this may mean that authors distinguished not between "true" and "sham" procedures, but between "strong" and "weak" influences. That is, there were no "true placebo" experiments. From this point of view, it would be better to fix the laser on a support at least 10 cm away from the skin, and do not illuminate the acupoints by visible light at all. Another source of errors may be the influence of the therapist (i.e. the electromagnetic radiation from his/her hands). If during the procedure the fingers of the therapist are as close to the skin as they are on Fig. 1, this may be the uncontrollable source of additional influence. From this point of view, it would be better to fix the laser on support, too, and don't keep it in hands. Taking into account these considerations, one can assume that deqi sensations were objectively excited in both study arms. So, one can assume that the main goal of the experiment -- distinguishing between "objective" and "subjective" reasons of deqi -- was not achieved. Competing interests Author of this comment has no competing interests.