Trigonelline

Trigonelline is a major metabolite of caffeine and nicotinic acid catabolism measurable in saliva as an objective marker of recent stimulant intake and metabolic clearance rate. Salivary trigonelline levels are inversely associated with sleep quality, as higher concentrations reflect residual caffeine load that delays sleep onset and reduces slow-wave sleep duration. It provides a quantitative readout of stimulant burden relative to recovery windows.