Length of neuro-physiological signals of emotion compared to feeling time
In "Simultaneous acquisition of corrugator electromyography and functional magnetic resonance imaging: A new method for objectively measuring affect and neural activity concurrently" Aaron et al. use face EMG to measure emotional reaction to photos. As shown in the figure below, the response only lasts a few seconds:



Getting a GSR response is more complicated due to the noise in the reading. In "Time-series analysis for rapid event-related skin conductance responses" by Bach et al., the authors figure out a mathematical approach for figuring out the event-related response. Both via a smoothed fitted gamma distribution and PCA component analysis are used below:



Both response measures seem to return to reference levels after 30 minutes.