For a study, researchers sought to understand that although open-label placebo (OLP) treatment appears to be effective in various medical conditions, it has not yet been studied in the treatment of insomnia. Furthermore, whether providing a plausible treatment rationale is required to obtain OLP effects must be assessed. Subjective and objective sleep measures were used to assess the sleep of 45 patients with primary insomnia over 2 nights. They were given a single OLP pill before the second night, with a treatment rationale (OLP+) or without (OLP−). When (M)ANOVAs revealed no differences in effects between the 2 OLP groups, the OLP+ group was compared to a previously assessed no pill control sample (NPC; n=23). The MANOVAs and ANOVAs did not reveal any significant interaction effects on the treatment group and assessment night. The OLP+ condition did not outperform either OLP− or NPC to improve patients’ sleep. Investigators’ findings did not support the general efficacy of OLP in primary insomnia, nor did they support differential effects based on treatment rationale. Possible explanations include the dosing scheme (i.e., single OLP application), the video presentation of the OLP rationale, and their study’s experimental rather than therapeutic nature. Larger sample size trials and longer-term OLP treatment in insomnia were required. Providing the rationale in person and in a clinical setting may be even more beneficial.