The relationship between chronotype and sleep behavior during rotating shift work: a field study

Abstract

Shift work, an essential part of our 24/7 society, inevitably leads to displacement of the habitual sleep period and thereby to misalignment of the internal circadian timing system with the rest–activity cycle and the environment. How interindividual differences in circadian organization affect sleep duration and timing during rotating shift work is not fully understood. The objective of this study was to assess the effect of chronotype, shift type, and their interaction on actigraphy-based sleep behavior in 74 police officers (20 women and 54 men; age [mean ± SD]: 32.1 ± 5.4 years) involved in rotating shift work throughout a 28- to 35-day work cycle consisting of morning, evening, and night shifts. Using linear mixed modeling, we found that chronotype was associated with sleep duration depending on the shift type: increasing morningness was correlated with longer sleep duration during series of consecutive morning shifts, while increasing eveningness was correlated with longer sleep duration during series of evening shifts. During series of night shifts, increasing eveningness was associated with a longer duration of the main sleep episode, but this relationship was attenuated and no longer significant when naps were taken into account due to increased napping in morning chronotypes during series of night shifts. Providing a detailed within-subject characterization of sleep behavior across a complete work cycle consisting of morning, evening, and night shifts, this study advances the understanding of the relationship between chronotype and sleep in rotating shift workers and supports the implementation of work schedules that take into account chronobiological principles.

Concordance of Chronotype Categorisations Based on Dim Light Melatonin Onset, the Morningness-Eveningness Questionnaire, and the Munich Chronotype Questionnaire

“…Furthermore, to simplify analyses and interpretations, distributions of continuous measures are often stratified into chronotype (e.g., early, intermediate, and late) categories. However, the approach to determining the cut-offs that separate categories is also inconsistent; most researchers apply percentile splits, e.g., [ 15 , 16 ], however, others use self-decided or recommended absolute cut-offs, e.g., [ 17 , 18 ].…”

Chronotype-specific Sleep in Two Versus Four Consecutive Shifts

“…Our findings showed that early types accumulated tremendous amounts of sleep loss over consecutive night shifts (66% lost > 5 h of sleep over 2N). Previous studies have reported early types to frequently nap before night shifts, attenuating sleep loss to such an extent that the relationship between a later chronotype and longer sleep for night shifts was no longer statistically significant ( Fischer et al, 2016 ; Kervezee et al, 2021 ). We observed a similar napping pattern in our study; yet, while naps did mitigate sleep loss during workdays, early types still had longer recovery sleep on their first day off than late types, suggesting that napping did not fully compensate for cumulative sleep loss.…”

“…Social jetlag has been associated with adverse health outcomes in both day and shift workers ( Henderson et al, 2019 , Parsons et al, 2015 , Roenneberg et al, 2012 ). There is a growing body of evidence suggesting that chronotype (i.e., the behavioral manifestation of underlying circadian rhythms) modulates sleep-wake behavior in day and shift schedules ( Kervezee et al, 2021 ; Korsiak et al, 2018 ; Razavi et al, 2019 ; Roepke and Duffy, 2010 ; van de Ven et al, 2016 ). For example, cross-sectional questionnaire and performance data collected in rotational shift workers demonstrated that late chronotypes on average perform better, sleep longer, and experience less circadian misalignment on night shifts compared with early chronotypes ( Juda et al, 2013a ; Vetter et al, 2012 ).…”

Diurnal variations in multi-sensor wearable-derived sleep characteristics in morning- and evening-type shift workers under naturalistic conditions

“…The rMEQ is not a shiftwork-specific instrument, and information on the individual work and rest schedules of the study participants is not available. Recent data suggest that the effect of chronotype on sleep duration and napping behavior during rotating shift work in police officers is modulated by the shift type (Kervezee et al 2021). We did not distinguish between day and night shifts nor between main sleep episodes and naps.…”

“…Furthermore, it is not known whether a sleep episode of less than 7-8 h was a nap and deliberately short, an unsuccessful attempt at a main sleep episode, or a consequence of the work pattern. For example, it cannot be excluded that the difference in phase position of minimal sleep duration may be impacted by shift schedules (Kervezee et al 2021). Given these limitations, we are bound to cautious, probabilistic statements.…”