Johanna Garefelt

Johanna Garefelt

PhD student

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Telephone 08-553 789 23
Visiting address Frescati Hagväg 16 A
Room 337
Postal address Stressforskningsinstitutet 106 91 Stockholm


A selection from Stockholm University publication database
  • 2018. Michelle Van Laethem (et al.). International Journal of Behavioral Medicine 25 (2), 231-242

    Purpose The aim of this longitudinal three-wave study was to examine (i) reciprocal associations among job demands, work-related perseverative cognition (PC), and sleep quality; (ii) PC as a mediator in-between job demands and sleep quality; and (iii) continuous high job demands in relation to sleep quality and work-related PC over time.

    Method A representative sample of the Swedish working population was approached in 2010, 2012, and 2014, and 2316 respondents were included in this longitudinal full-panel survey study. Structural equation modelling was performed to analyse the temporal relations between job demands, work-related PC, and sleep quality. Additionally, a subsample (N = 1149) consisting of individuals who reported the same level of exposure to job demands during all three waves (i.e. stable high, stable moderate, or stable low job demands) was examined in relation to PC and sleep quality over time.

    Results Analyses showed that job demands, PC, and poor sleep quality were positively and reciprocally related. Work-related PC mediated the normal and reversed, direct across-wave relations between job demands and sleep quality. Individuals with continuous high job demands reported significantly lower sleep quality and higher work-related PC, compared to individuals with continuous moderate/low job demands.

    Conclusion This study substantiated reciprocal relations between job demands, work-related PC, and sleep quality and supported work-related PC as an underlying mechanism of the reciprocal job demands-sleep relationship. Moreover, this study showed that chronically high job demands are a risk factor for low sleep quality.

  • 2016. Daniela Wey (et al.). Chronobiology International 33 (10), 1422-1432

    Daytime workers tend to have shorter sleep duration and earlier sleep onset during work days than on days off. Large individual differences in sleep onset and sleep duration may be observed on work days, but work usually synchronizes sleep offset to a similar time. The present study describes individual differences in sleep behaviour of 48 daytime workers (25 men, aged 20-58 years) from an iron ore mine in Northern Sweden. The aim of the study was to determine whether differences in sleep patterns during work days were associated with the outcomes of sleepiness and sleep complaints. Cluster analysis was used to group workers into two categories of sleep onset and sleep duration. The "Late Sleep Onset" cluster comprised workers who slept 1.30 h later than the "Early Sleep Onset" cluster (p < 0.0001 for all weekdays). The "Long Sleep Duration" cluster slept 1.10 h longer than the "Short Sleep Duration" cluster (p < 0.0002 for work nights). The "Late Sleep Onset" cluster reported less refreshing sleep (p < 0.01) and had lower sufficient sleep scores (p < 0.01) than the "Early Sleep Onset" cluster. The "Short Sleep Duration" cluster also reported lower scores for sufficient sleep (p < 0.04) than the "Long Sleep Duration" cluster. For combined characteristics (phase and duration), workers with a late phase and short sleep duration reported greater sleep debt and sleepiness than workers with an early phase and short sleep duration (p < 0.02). Work schedule and commuting time modulate both sleep phase and sleep duration independently. Workers, classified as having an intermediate sleep phase preference, can organize their sleep time in order to minimize sleep debt and sleepiness symptoms. Individual differences in sleep phase and duration should be considered when promoting well-being at work even among groups with similar sleep needs. In order to minimize sleep debt and sleepiness symptoms, successful sleep behaviour could be promoted involving extend use of flexitime arrangement (i.e. later starting times) and reduce use of alarm clocks.

  • 2015. Elaine Cristina Marqueze (et al.). PLoS ONE 10 (4)

    OBJECTIVES: This study aimed to investigate the relationship between individual natural light exposure, sleep need, and depression at two latitudes, one extreme with a few hours of light per day during winter, and the other with equal hours of light and darkness throughout the year.

    METHODS: This cross-sectional study included a sample of Brazilian workers (Equatorial, n = 488 workers) and a Swedish sample (Arctic, n = 1,273).

    RESULTS: The reported mean total natural light exposure per 4-week cycle differed significantly between the Equatorial and Arctic regions. However, shiftworkers from both sites reported similar hours of natural light exposure. Short light exposure was a predictor for insufficient sleep.

    CONCLUSION: Reduced exposure to natural light appears to increase the perception of obtaining insufficient sleep. Arctic workers were more prone to develop depression than Equatorial workers.

Show all publications by Johanna Garefelt at Stockholm University

Last updated: January 18, 2019

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