OBJECTIVES: To understand how shift work disorder (SWD) affected the lives of shift workers (SWs) and how SWD was diagnosed from the perspective of health care professionals (HCPs) and SWs. METHODS: Two separate online surveys were administered to: (1) SWs with/out SWD and (2) HCPs. Participation in the SWs survey required ≥21 hours per week working shifts in the previous 2 weeks, a diagnosis of SWD or ≥10 score on the Epworth Sleepiness Scale (ESS), and ≥5 score on any of the subscales of the Sheehan Disability Scale (SDS). Participation in the HCP survey required ≥3 years in pre-designated specialties and at least 75% of their time spent in patient care. RESULTS: A total of 260 respondents complete the SWs survey and 673 the HCP survey. SW negatively impacted respondents’ energy level, social life, and emotional and physical health. SWs also reported a loss of concentration (87%), mistakes (69%), and an injury (11%) at work. Many respondents used caffeine and 57% of diagnosed respondents received prescription medication to treat SWD symptoms. Of those SWs without diagnosed SWD, 23% denied having excessive sleepiness despite scoring ≥10 on the ESS and having functional impairment (SDS). For those SWs who consulted with their HCPs, SWs initiated this conversation more than HCPs (82% vs. 13%). HCPs believe that 67% of total SWD is never suspected by physicians and that 50% of SWD is undiagnosed because SWD is often masked by other conditions and/or misdiagnosed. CONCLUSIONS: Respondents reported that excessive sleepiness and insomnia associated with SW seriously impacted their lives at home and at work. SWs do not always recognize their SWD symptoms and are more likely to initiate a discussion of those symptoms than HCPs. HCPs believe that SWD is often missed as it is masked by other comorbidities or misdiagnosed. This research was sponsored by and conducted in collaboration with Cephalon, Inc., Frazer, PA.