I don't understand how they could conclude that their sleeping caps had any effect when they apparently went into the study with the belief that they work and d

I don't understand how they could conclude that their sleeping caps had any effect when they apparently went into the study with the belief that they work and decided not to have a placebo control group because it would be unethical. As these patients were all ill, many undergoing olmesartan treatment with therapeutic intent, we decided that ethical considerations precluded the distribution of “placebo caps” without the silver threads. And they were apparently distributed to those that requested them, likely those that already thought they would work: Sleeping caps” were sewn and, upon informed request, distributed free of charge to members of our follow-up olmesartan cohort.