How are LCT and sleep related?

The relationship between LCT (lactase gene) and sleep is not directly established in scientific literature. LCT variants determine lactase persistence, i.e., the ability to digest lactose in adulthood. A plausible indirect link: lactose intolerance can cause gastrointestinal discomfort (bloating, cramps, diarrhea) after dairy consumption, which may disrupt sleep. However, this is a mechanistic hypothesis without direct human evidence linking LCT genotype to sleep quality or duration. No GWAS or clinical studies have identified LCT as a significant sleep-associated gene. Therefore, the evidence level is 'mechanistic' or 'unclear'. For sleep issues, focus on proven factors like sleep hygiene, stress, and diet timing. If lactose intolerance is suspected, an elimination diet or medical test is more informative than a genetic test. LCT testing alone is not recommended for sleep optimization.