Table 3 Overview of saliva melatonin levels in AD as compared to controls. ↓ means a significant reduction in saliva melatonin in AD when compared to controls. = means no significant difference in saliva melatonin in AD when compared to controls. ✖ means no data comparing saliva melatonin levels between AD and controls were available. A black star ★ was attributed per NOS criterium per category (selection, comparability, exposure) met. Stars were kept white ☆ if the NOS criterium in the corresponding category was not met

From: Melatonin levels in the Alzheimer’s disease continuum: a systematic review