Evidence check: CYP2C19 in the context of sleep

CYP2C19 variants (e.g., *2, *3, *17) alter the activity of a liver enzyme that metabolizes many drugs, including sleep-relevant medications such as diazepam, certain benzodiazepines, and some antidepressants (e.g., citalopram). In 'poor metabolizers,' these drugs may persist longer and affect sleep architecture; in 'ultrarapid metabolizers,' effects may be too short. However, direct, medication-independent links between CYP2C19 and sleep quality are poorly supported. Most evidence comes from pharmacokinetic and mechanistic studies. Consumer DNA reports often overstate clinical significance – a positive finding alone does not justify dose changes without medical supervision. Safety note: self-adjusting sleep medications based on genetic results can be dangerous. Evidence: mechanistic/mixed.