Is LCT useful for sleep?

The question of whether LCT (lactase persistence) is useful for sleep cannot be answered from the provided context. LCT governs lactose digestion; a direct effect on sleep is not scientifically established. Indirectly, lactose intolerance could cause discomfort after evening dairy intake, potentially disturbing sleep – but this is individual and not genotype-driven. The evidence level is 'unclear'. Caveat: No clinical recommendation can be derived from genetic tests.