[PDF] Low, but not high, doses of melatonin entrained a free-running blind person with a long circadian period | Semantic Scholar

The dim-light melatonin offset (DLMOff), even when operationally defined at thresholds less than 10 pg/ml, appears to be confounded by amplitude in this study; in such cases, it may be preferable to use the melatonin synthesis offset (SynOff) because it is not confounding by amplitude and because, theoretically, it is temporally closer to the endogenous mechanism signaling the offset of production.