A device and method measuring at least one parameter related to the blood of a subject, by emitting light with at least one emitter at least one wavelength within the spectral range of 380 980 nm toward a body part containing at least one wavelength. Spatially resolved reflectance measurements are obtained by capturing light reflected by the body part with at least one reflectance detector. At least one of the absorption coefficient and the reduced scattering coefficient of the blood component of the body part at each of the wavelengths is extracted from the measurements. The temporal derivatives of the at least one of the absorption coefficient and the reduced scattering coefficient is extracted, and at least one blood related parameter is calculated using the temporal derivatives.