MedicalResearch.com Interview with:
Tea Lallukka, PhD
Finnish Institute of Occupational Health &
University of Helsinki, Hjelt Institute, Department of Public Health
University of Helsinki, Finland
Medical Research: What are the main findings of the study?
Dr. Lallukka: Our study used nationally representative survey data linked with
register data on medically certified sickness absence among working
-aged Finnish women and men. We showed consistent associations between
insomnia symptoms, sleep duration, and being tired and sickness
absence. The follow-up lasted around 7 years.
Sickness absence days were derived from comprehensive registers from
the Social Insurance Institution of Finland. The associations were
broadly similar among women and men. Furthermore, they remained even
after considering key correlates of sleep and sickness absence
including socioeconomic position, working conditions, health
behaviors, obesity, and mental and physical health. Health data were
derived from physical examination conducted by field physicians. These
data are more objective, and help provide more robust evidence. We
further covered all key sleep disturbances and sleep duration for more
comprehensive understanding about the contribution of sleep to
sickness absence. Finally, a novel method developed by the authors
(Härkänen & Kaikkonen) allowed us to estimate the difference in
sickness absence days per working year among those reporting and not
reporting different sleep disturbances. Using the difference in days
absent from work, we were further able to estimate the hypothetical
direct costs of sickness absence highlighting notable societal
significance of sleep. Thus, a large part of all costs of sickness
absence are attributable to poor sleep. For example, those sleeping 5
hours or less or 10 hours or more, were absent from work ca 5-9 days
more, as compared to those with optimal sleep length. The optimal
sleep length with the lowest risk of sickness absence was 7 hours 46
minutes for men and 7 hours 38 minutes for women.
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