Implementations disclosed herein provide a monitoring technology. In one implementation, a monitoring system measures whole body biometric levels by analysis of changes in vascular volume caused by pulsatile pressure waves and in tissue volume in response to the pulsatile pressure. The monitoring system includes a monitoring device, which uses a light-based measurement technique to measure biometric levels during different activities and at rest. A light source operatively connected to a light sensor, transmits light, reflectively or transmissively, through tissue. The light sensor detects absorption of the light. Based on wavelength measurements of the detected light, the monitoring device produces a PPG waveform representing characteristic effects of certain physiological parameters. In one implementation, operating contexts are sensed in a monitoring device. A monitoring profile is selected based on the sensed operating contexts. A biometric is computed based on the PPG waveform and on the selected monitoring profile.
