Chronotype in relation to shift work: A cohort study among 37,731 female nurses

Area of Science:

• Occupational Health
• Sleep Medicine
• Chronobiology

Background:

• Shift work is prevalent in nursing and can disrupt circadian rhythms.
• Individual differences in chronotype (natural inclination towards morning or evening activity) may influence tolerance to circadian disruption.
• Understanding the relationship between chronotype, sleep patterns, and shift work is crucial for occupational health in nursing.

Purpose of the Study:

• To examine the association between chronotype, sleep timing, shift type preference, and sleep problems in a large cohort of nurses.
• To investigate the stability of chronotype over time in this population.
• To determine if chronotype modifies the impact of shift work on sleep.

Main Methods:

• A longitudinal study of 37,731 Dutch female nurses using baseline (2011) and follow-up (2017) questionnaires.
• Data collected included job history, shift type preference, chronotype, preferred sleep-wake times, and sleep problems (MOS-SPI-II).
• Statistical analyses included linear regression, ordered logistic regression, and Poisson regression.

Main Results:

• Later chronotypes exhibited later midsleep times in work-free periods.
• Individuals with later chronotypes showed increased preference for night and evening shifts and decreased preference for day and morning shifts.
• Intermediate chronotypes reported fewer sleep problems compared to definite morning or evening types.

Conclusions:

• Chronotype is significantly associated with sleep-wake timing, shift type preference, and sleep problems among nurses.
• These findings suggest that chronotype should be considered as a potential effect modifier in studies examining the health consequences of shift work-induced circadian disruption.
• The study underscores the importance of aligning shift work schedules with individual chronotypes to mitigate sleep problems and potential health risks in nursing.