Myths vs facts: Selen and Schlaf

The question of selenium and sleep illustrates the gap between plausible mechanisms and solid evidence. Selenium is an essential trace element that acts as a cofactor for selenoproteins (e.g., glutathione peroxidases, thioredoxin reductases), supporting antioxidant defense and thyroid function. Inadequate thyroid activity (hypothyroidism) can cause fatigue and sleep disturbances, so selenium deficiency could theoretically impair sleep. However, no high-quality clinical trials demonstrate a direct causal effect of selenium supplementation on sleep quality in healthy individuals. Evidence is limited to observational studies and plausible but unproven mechanisms. Consumer DNA tests that claim to predict a 'selenium need' often overstate the clinical relevance of single SNPs (e.g., in GPX1 or SEPP1). Effect sizes are small, and diet has a much larger impact. Bottom line: Adequate selenium intake is important for overall health, but the claim that selenium specifically improves sleep is not evidence-based. Deficiency should be assessed by a physician before considering supplements.