As reported in the medical journal Cephalalgia, the subjects said they felt an increase in pain or discomfort during 68 per cent of all trials. The degree of symptoms was not associated with the order of trials.

• 在医学杂志Cephalalgia上发表的研究报告表明，在68%25的试验中，研究对象称感到头痛或不适症状加重。而症状的轻重程度与试验的顺序没有关系。