Is Selen useful for sleep?

The provided context does not contain direct evidence regarding selenium's usefulness for sleep. Selenium is an essential trace mineral involved in antioxidant defense and thyroid hormone metabolism. Some observational studies have reported associations between low selenium levels and poor sleep quality, but the evidence is weak and primarily mechanistic or epidemiological. No robust randomized controlled trials confirm a causal benefit of selenium supplementation for sleep. Furthermore, excessive selenium intake can be toxic (selenosis). Therefore, recommending selenium specifically for sleep improvement is not supported by current high-quality evidence. A balanced diet typically provides adequate selenium; supplementation should only be considered if deficiency is confirmed and under medical supervision. Evidence: unclear.