Evidence check: CLOCK in the context of fertility

The evidence for a direct link between CLOCK gene variants and fertility is weak and primarily mechanistic. CLOCK is a core circadian rhythm gene, and circadian disruption is associated with hormonal imbalances, menstrual irregularities, and reduced egg and sperm quality. However, most data come from animal studies or small human observational studies; large GWAS or clinical trials confirming specific CLOCK polymorphisms as fertility predictors are lacking. MyBody-X's Hormon & VitalCheck für Frauen tests relevant hormones like cortisol, TSH, and prolactin, but not CLOCK directly. Interpreting CLOCK variants from consumer DNA tests is not clinically actionable. Focus should be on lifestyle factors such as sleep hygiene, stress management, and balanced nutrition. For unresolved infertility, medical evaluation is essential. Evidence: mechanistic, insufficient for recommendations.