Sleep duration and quality in permanent night work: an observational field study

Kirsten Nabe-Nielsen*, Ann Dyreborg Larsen, Anne Emily Saunte Fiehn Arup, Mette Sallerup, Vivi Schlünssen, Anne Helene Garde, Åse Marie Hansen

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

PURPOSE: Permanent night workers conceivably show better adaptation of circadian rhythms to night work than shift workers and therefore better possibilities of obtaining sufficient sleep of good quality after night shifts. We investigated the effect of night shifts including number of consecutive shifts on sleep among self-selected permanent night workers, and studied if the effect of night shifts differed between morning and evening types and compared with 3-shift workers.

METHODS: The study population included 90 permanent night workers followed for 14 days (warehouse workers, 1228 observation days, 80% males). For comparison, we included 70 3-shift workers followed for 26 days (police officers, 1774 observation days, 100% men). Total sleep time (TST), primary sleep duration (PSD), and sleep efficiency were assessed by actigraphy. Measures of sleep quality and diurnal type were self-reported.

RESULTS: Among permanent night workers, TST, PSD, difficulties falling asleep, disturbed sleep, and the number of awakenings decreased after night shifts compared with days without night work. Sleep efficiency, difficulties awakening, and non-refreshing sleep increased. More consecutive night shifts were associated with shorter TST and PSD. Sleep outcomes did not differ by diurnal type. Permanent night workers had fewer awakenings after night shifts than 3-shift workers, but no other differences were observed.

CONCLUSION: This study does not provide evidence that supports recommendation of permanent night work to reduce adverse effects of night shifts on sleep. A limited number of consecutive night shifts is recommended to reduce accumulation of sleep debt.

Original languageEnglish
JournalInternational Archives of Occupational and Environmental Health
Volume97
Pages (from-to)733–743
Number of pages11
ISSN0340-0131
DOIs
Publication statusPublished - 2024

Bibliographical note

© 2024. The Author(s).

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