A new study challenges the assumption behind conventional clinical trial averaging by showing that a nasal spray’s brain impact varies by week, potentially explaining why a promising drug candidate appeared to fail. The work highlights how temporal variation can confound fixed-dose trial readouts—especially when individual pharmacology or exposure dynamics shift during the study period. The findings point to the need for trial designs that account for time-dependent effects, rather than assuming uniform response across participants and days. For developers, the implication is direct: efficacy signals may be obscured if dosing-to-effect relationships fluctuate across trial windows. While the excerpt does not name the drug or study population details, the mechanism-focused takeaway is that averaging may miss clinically relevant variability patterns.