The invention concerns a measuring device for measuring physiological data of a mammal. The measuring device comprises a measuring unit (10), to be worn by the mammal (Z), with a first and second module (12, 14) to be arranged on opposite sides of a skin part (H) of the mammal. The first module comprises a light source (122) for generating light (L) and the second module comprises a sensor unit (142) for measuring an intensity of a fraction (Lm) of the light (L), received via that skin part, and for delivering a measuring signal (S L ) which is indicative of the measured value of the intensity. The measuring device is provided with synchronization means for pulsewise activating the light source synchronously with the second module, wherein the measuring signal is indicative of the value of the intensity measured during the pulsewise activation. The synchronization means comprise an energy transmitting unit (126 144) which is part of one of the first and the second module, and a detector (148124) which is part of the other one of the first and the second module, wherein in an operating condition the energy transmitting unit (126144) pulsewise generates an electromagnetic field, and the detector receives this field and generates therefrom a supply voltage for use in that other module.
