Is ACTN3 useful for Schlaf?

The ACTN3 gene variant (R577X) is primarily known for its role in muscle fiber composition, influencing sprint vs. endurance performance. There is no strong scientific evidence that it is useful for sleep. Some GWAS have reported weak associations with sleep traits (e.g., sleep duration), but these are not replicated and effect sizes are negligible. The evidence is insufficient to guide any sleep-related recommendation. Sleep quality is mainly determined by light exposure, stress, caffeine, and sleep hygiene—not a single gene. Therefore, testing ACTN3 for sleep purposes is not evidence-based and not recommended.