Evidence check: Selen in the context of Schlaf

The link between selenium and sleep is not well-established. Selenium is an essential trace mineral that functions as a cofactor for antioxidant enzymes (e.g., glutathione peroxidases) and supports thyroid hormone metabolism—both pathways that could theoretically influence sleep regulation. Some observational studies have reported associations between low selenium levels and poorer sleep quality, but the evidence is limited to mechanistic plausibility and cross-sectional data. High-quality randomized controlled trials specifically testing selenium supplementation for sleep improvement are lacking. Moreover, selenium has a narrow therapeutic window; chronic excess intake can lead to selenosis (toxic symptoms). Therefore, supplementation without prior assessment of selenium status (e.g., via blood or hair analysis) is not advised. In the context of consumer health tests or supplements, selenium is sometimes marketed as a sleep aid, but this is not supported by robust human evidence. For sleep issues, evidence-based approaches include good sleep hygiene, stress management, and checking for common deficiencies (iron, vitamin D, magnesium). Evidence: mechanistic/observational. Sources: none specific in provided context.