Myths vs facts: CYP2D6 and sleep

CYP2D6 is a cytochrome P450 enzyme responsible for metabolizing many drugs, including some that affect sleep (e.g., certain antidepressants, antipsychotics, beta-blockers). A common myth is that CYP2D6 genotype directly determines sleep quality or circadian rhythm. In fact, there is no robust evidence for a direct effect on sleep. The influence is indirect: depending on metabolizer status (poor, intermediate, extensive, ultrarapid), the clearance of medications can vary, potentially leading to side effects such as drowsiness or insomnia in sensitive individuals. Without medication use, CYP2D6 has negligible impact on healthy sleep. Consumer DNA tests that claim a direct link overstate the evidence. The scientific support is primarily mechanistic; randomized controlled trials are lacking. Caution is warranted: being labeled a 'poor metabolizer' alone does not justify sleep medication adjustments without medical supervision.