Cataplexy is an intriguing example of how emotions can trigger muscle weakness by activating neural pathways. When associated with excessive daytime sleepiness, cataplexy is considered pathognomonic of narcolepsy. A questionnaire was administered to 55 patients with narcolepsy-cataplexy and 47 comparison subjects with obstructive sleep apnea. The area under the receiver-operating curve was 0.94 for the combination of muscle weakness with laughter and ability to hear during the episode. A 51-item questionnaire succeeds in identifying cataplexy in narcolepsy-cataplexy patients measured up against a comparison group. In the future, an abbreviated survey with these two questions should identify cataplexy with high sensitivity and specificity. These selected questions could subsequently be included into screening tools for use with different patient populations.