How are Ferritin and Schlaf related?

Ferritin is an iron storage protein. Its link to sleep is primarily through iron deficiency: low ferritin levels (below 50–70 µg/L) are associated with Restless Legs Syndrome (RLS) and consequent sleep disruption. Conversely, iron overload (hemochromatosis) may also impair sleep. The evidence is mostly mechanistic and observational; there are no strong randomized trials proving a direct causal effect of ferritin on sleep quality. A ferritin test can be useful when investigating sleep issues, but results must be interpreted in a clinical context.