What role does FT3 play in Schlaf?

The provided context does not address the role of FT3 (free triiodothyronine) in sleep. In general, FT3 is the active thyroid hormone that regulates metabolism, body temperature, and circadian rhythms. Both hyperthyroidism (high FT3) and hypothyroidism (low FT3) can impair sleep quality, causing difficulty falling asleep, frequent awakenings, or altered sleep stages. Evidence is based on clinical endocrinology and observational studies; direct causal pathways are not fully established. Single-point FT3 measurements from home tests lack sufficient evidence to guide sleep interventions. Persistent sleep issues warrant a medical evaluation that includes thyroid function.