Evidence check: Ferritin in the context of sleep

Ferritin is an iron-storage protein and a key biomarker for body iron status. Low ferritin levels can indicate iron deficiency, which is linked to sleep disturbances such as Restless Legs Syndrome (RLS). RLS causes uncomfortable sensations in the legs and an irresistible urge to move them, significantly impairing sleep onset and quality. However, the evidence for a direct causal relationship between ferritin and sleep in healthy individuals without RLS is limited and largely based on mechanistic reasoning and observational studies. Some research shows that iron supplementation in confirmed iron deficiency can reduce RLS symptoms and improve sleep. Yet ferritin is an acute-phase reactant, meaning it can be elevated during inflammation, so a normal ferritin level does not always rule out functional iron deficiency. Interpretation of ferritin values requires clinical context. Consumer lab tests measuring ferritin can provide a hint but cannot diagnose sleep disorders. Overall, the evidence is moderate to unclear, as no large randomized trials have specifically examined ferritin and sleep in the general population.