AIM: The aim of this study is to investigate premorbid sleep reactivity as a vulnerability to incident shift work disorder (SWD), and related changes in depression as well as anxiety following a transition to a rotating shifts work schedule.
METHODS: This is a longitudinal study with two waves of data collection. The community-based sample included normal sleeping non-shift workers (N = 96; 62.5% female; 47.9 ± 13.3 years) without a lifetime history of insomnia or baseline excessive daytime sleepiness who transitioned to rotating shift work one year later. Participants reported demographic characteristics, trait sleep reactivity on the Ford Insomnia Response to Stress Test, depression symptoms on the Quick Inventory of Depression Symptomatology, and anxiety symptoms on the Beck Anxiety Inventory. SWD was determined based on significant sleep disturbance and/or excessive sleepiness in the context of working in a rotating-shift schedule.
RESULTS: Analyses revealed that the odds were over five times greater for highly sleep-reactive individuals to develop SWD after transitioning to rotating shifts (OR = 5.59, p = 0.04). Nearly 90% of participants who suffered from SWD were accurately identified as high risk at one year before disease onset. Furthermore, individuals who developed SWD reported greater increases in symptoms of depression and anxiety. Finally, analyses revealed significant indirect effects wherein high sleep reactivity increased risk for SWD, which led to greater severity of anxiety and depression symptoms.
CONCLUSIONS: The Ford Insomnia Response to Stress Test (FIRST) accurately identifies a focused target population in which the premorbid psychobiological processes complicit in SWD onset and progression, as well as shift work-related depression and anxiety changes, can be better investigated, thus improving future preventative efforts.
