Chronotype distinctness a key risk factor for emotional and cognitive disruption in shift working nurses

The prevalence of shift work-centric industries and the rise of flexible working render it crucial to investigate the health risks posed by unnatural patterns of work and sleep. Shift working in healthcare has been linked to emotional dysregulation, reduced alertness, and cognitive impacts, with Shift Work Disorder (SWD) classified as a circadian rhythm sleep-wake disorder in the DSM-5. These impacts have historically been attributed to schedule-related sleep disturbances; however certain individuals appear more acutely affected. One measure of individual inflexibility to altered routines is chronotype distinctness, an amplitude dimension of the Caen Chronotype Questionnaire (CCQ). Here, we use Structural Equation Modelling (SEM) to unravel the mechanisms by which sleep and chronotype distinctness govern the neuropsychiatric symptom profiles of a cohort of National Health Service (NHS) shift workers (n=102). We constructed a measurement model, extracting latent constructs from questionnaires for sleep disturbances (PSQI), chronotype distinctness (CCQ), mood disorder (MDQ), depression (PHQ8) and emotional reactivity (ERS), and cognitive assessments. Correlations were identified between constructs, then translated into two SEMs - day and rotating shifts respectively - with sleep and distinctness as predictors of detrimental effects. Models were tested for direct effects, significant paths, and overall model fit. We found that, whilst sleep governed fatigue-based symptoms in day-shift workers, chronotype distinctness determined the severity of adverse effects in rotating-shift workers, including mood disorders and cognitive impairments. We surmise that high chronotype distinctness should be considered a risk factor for adverse effects surrounding night and rotating-shift work, and that interventions should incorporate chronotype-specific remediation.

SUMMARY QUESTIONS

What is already known on this topic: It is understood that sleep and schedule disturbances caused by shift working have widespread detrimental effects on health including emotional dysregulation, reduced attention, alertness and cognitive function.

What this study adds: Here, we explore the role that a new measure of individual inflexibility – chronotype distinctness – may play in governing the detrimental effects of shift work, that have previously been attributed to sleep disturbances alone.

How this study might affect research, practice or policy: These findings suggest that chronotype distinctness should be considered as a personal risk factor for worse emotional and cognitive effects in shift workers; hence, workplace accommodations and interventions that consider chronotype may produce more effective remediative results.