What to watch with Magnesium and sleep?

Magnesium is often marketed as a sleep aid, but the evidence is mixed. Some studies suggest that magnesium can improve sleep quality in people with a confirmed deficiency, particularly reducing sleep onset latency and improving sleep efficiency. However, the effect in individuals with normal magnesium levels is small or non-significant. The research relies mainly on small trials and mechanistic reasoning (e.g., GABA receptor binding, melatonin regulation). High-dose magnesium (>350 mg/day as supplement) can cause diarrhea, nausea, and abdominal cramps; in kidney impairment, there is a risk of hypermagnesemia with serious side effects. Consumer blood tests or DNA variants (e.g., TRPM6) have limited predictive value for actual magnesium needs. Recommendation: For sleep issues, prioritize sleep hygiene and medical evaluation; supplement magnesium only if deficiency is confirmed or under medical guidance. The evidence is moderate – not strong enough for a general recommendation.