Is CLOCK useful for longevity?

Based on the provided context, there is no direct information about the CLOCK gene. However, CLOCK is a core circadian rhythm gene. Circadian disruption is linked to aging and age-related diseases, but evidence for specific CLOCK variants directly influencing human longevity is limited to mechanistic and GWAS studies with small effect sizes. Therefore, a consumer DNA test for CLOCK is not a reliable predictor of lifespan. Lifestyle factors like sleep, diet, and exercise have stronger evidence. The evidence level is 'mixed' – plausible mechanism but weak human data. No specific sources from the given context.