What to watch with FUT2 and Schlaf?

FUT2 (fucosyltransferase 2) determines secretor status and influences gut microbiome composition and vitamin B12 absorption. Non-secretors (inactive FUT2) often have altered gut bacteria and lower B12 levels. B12 deficiency can cause fatigue and sleep disturbances, but direct evidence linking FUT2 variants to sleep quality is weak and indirect. No official sleep guidelines consider FUT2 genotype. For sleep issues, focus on sleep hygiene, circadian rhythm, and medical evaluation. Consumer DNA tests rarely include sleep-specific genes like CLOCK or PER. If B12 deficiency is suspected, a blood test (holotranscobalamin, MMA) is more reliable. Evidence: mechanistic/unclear. Caveat: effect size small; do not rely on DNA alone for sleep management.