In one embodiment, one or more computer-readable non-transitory storage media embody software that is operable when executed to determine, based on cardiac-activity data, a shift in sympathovagal balance (SVB) during the period of time； obtain an emotional-state characteristic the emotional-state characteristic being based on brain-wave activity data； and determine, based on the SVB shift and the emotional-state characteristic, an estimate of an emotional state of the user during the period of time.
