Abstract
BACKGROUND: To study whether sleep duration, sleep debt (difference between sleep need and duration), and insomnia severity at baseline would predict increased prevalence of infections 1 year later. METHODS: In total, 861 participants recruited from the Norwegian Primary Care Research Network completed a baseline survey about sleep and were invited for follow-up 1 year later. The response rate at follow-up was 60.5%, rendering 521 patients eligible for analyses. At baseline the participants completed questions about sleep habits and insomnia symptoms (insomnia severity index), and at follow-up they responded to whether they had experienced various infections during the last 3 months and whether they experience more infections than peers. RESULTS: Participants with normal sleep duration, no sleep debt and no insomnia at baseline reported the lowest prevalences of infections at 1-year follow-up. In the adjusted analyses, long sleep duration (>9 h, present only in 11 participants) increased the odds of influenza-like illness, gastrointestinal infection, and experiencing more infections than peers by about four times, whereas short sleep duration (<6 h) doubled the odds of skin infection. Compared to no sleep debt, ≤2 h sleep debt doubled the odds of skin infection and >2 h sleep debt tripled the odds of experiencing more infections than peers. Insomnia doubled the odds of any type of infection and influenza-like illness, and more than tripled the odds of gastrointestinal infection and experiencing more infections than peers. CONCLUSIONS: This longitudinal study supports the notion that people who have insufficient sleep are at increased risk of infections.