Myths vs facts: FUT2 and sleep

Claims that FUT2 (fucosyltransferase 2) directly affects sleep are not supported by evidence. FUT2 determines secretor status and influences gut microbiota composition and vitamin B12 absorption. While some research links the gut microbiome to sleep, no robust association between specific FUT2 variants and sleep traits (duration, efficiency, disorders) has been found in GWAS or candidate studies. The evidence is mechanistic and speculative at best. Consumers should be wary of marketing that labels FUT2 a 'sleep gene'. Sleep regulation is complex, involving circadian genes (CLOCK, PER3), lifestyle, and environment. A DNA test for FUT2 provides no actionable sleep insights. Polygenic scores claiming to predict sleep from FUT2 are unreliable. Evidence: unclear. Sources: none.