Ethnic differences in self-reported sleep duration in the Netherlands - the HELIUS study

Background: We investigated ethnic differences in sleep duration, and the contribution of socio-economic status (SES) to the observed differences in Amsterdam, the Netherlands. Methods: 6959 participants (aged 18-71 years) from the multi-ethnic HELIUS cohort were studied. Outcome variables were short sleep (<7 h/night) and long sleep (≥9 h/night). Comparisons among groups were made using Prevalence Ratios (PRs). Results: Ethnic minority groups were more likely than ethnic-Dutch to report short sleep, with prevalence ranging from 15.1% to 49.7% in men and 16.3% to 41.4% in women. Among men, the age-adjusted PRs ranged from 2.15 (95% CI 1.72-2.69) in Turkish to 3.31 (2.75-3.99) in Ghanaians; and among women, from 1.62 (1.30-2.01) in Turkish to 2.52 (2.15-2.95) in African-Surinamese, respectively. The prevalence of long sleep was significantly higher only in Moroccan men and all the ethnic minority women than in ethnic-Dutch women except for African-Surinamese. Adjustment for SES explains the ethnic difference in long sleep, but not for short sleep. Conclusion: Ethnic minority groups reported more short sleep than ethnic-Dutch, while there were no ethnic differences in long sleep. Further study is needed to investigate how this finding on short sleep may contribute to ethnic differences in health outcomes.