TY - JOUR T1 - Association of changes in work shifts and shift intensity with change in fatigue and disturbed sleep: a within-subject study JO - Scandinavian Journal of Work, Environment & Health PY - 2018/7VL - 44 IS - 4 SP - 394 EP - 402 AU - Härmä, Mikko AU - Karhula, Kati AU - Ropponen, Annina AU - Puttonen, Sampsa AU - Koskinen, Aki AU - Ojajärvi, Anneli AU - Hakola, Tarja AU - Pentti, Jaana AU - Oksanen, Tuula AU - Vahtera, Jussi AU - Kivimäki, Mika M3 - doi: 10.5271/sjweh.3730 UR - https://www.sjweh.fi/show_abstract.php?abstract_id=3730 KW - disturbed sleep KW - fatigue KW - forward-rotating shift KW - insomnia KW - night shift KW - night work KW - older worker KW - shift KW - shift intensity KW - shift interval KW - shift work KW - shift worker KW - sleep KW - sleep duration KW - sleep length KW - sleep problem KW - sleepiness KW - within-subject study KW - working hours N2 - '

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OBJECTIVES ': 'The aim of this study was to examine whether changes in work shifts and shift intensity are related to changes in difficulties to fall asleep, fatigue, and sleep length.

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METHODS ': 'Questionnaire responses of hospital employees (N=7727, 93% women) in 2008, 2012, 2014 and 2015 were linked to daily-based records of working hours during three months preceding each survey. We used conditional logistic regression and longitudinal fixed-effects analyses to investigate odds ratios (OR) and 95% confidence intervals (CI) for each 25% within-individual change in the proportion of working hour characteristics in relation to changes in fatigue, difficulties to fall asleep, and 24-hour sleep length.

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RESULTS ': 'Change in night but not in morning or evening shifts was associated with parallel changes in odds for longer sleep length (OR 1.45, 95% CI 1.28–1.64) and fatigue during free days (OR 1.38, 95% CI 1.16–1.64). Similarly, short shift intervals and having >2 but not >4 consecutive night shifts were associated with increased odds of fatigue during work and difficulties to fall asleep (OR 1.42, 95% CI 1.19–1.72 and OR 1.10, 95% CI 1.05–1.19, respectively). Among workers aged ≥50 years, the associations were the strongest between night shifts and longer sleep (OR 2.24, 95% CI 1.52–3.81) and between higher proportion of short shift intervals and fatigue during free days (OR 1.68, 95% CI 1.10–2.54).

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CONCLUSIONS ': 'Among shift workers with fatigue or sleep problems, decreasing the proportion of night shifts and quick returns and giving preference to quickly forward-rotating shift systems may reduce fatigue.

SN - 0355-3140 ER -