Novel tools and techniques for wearable device vital signs monitoring are provided. An apparatus system includes a remote device, and a wearable device in communication with the remote device. The wearable device includes a polychromatic light source, a spectral sensor, a processor, and a non-transitory computer readable medium comprising instructions executable by the processor. The wearable device is configured to illuminate, via the polychromatic light source, a perfused tissue of the body of the patient, receive, via the spectral sensor, a resultant signal from the body of the patient, and determine a spectral property of the resultant signal. The wearable device may then determine a vital sign of the patient based, at least in part, on a lookup table and the spectral property of the resultant signal.
