Cho and Irwin (2015) also suggest that research should investigate the possibility that there may be interventions that could influence immune processes and thus reduce the risk of illness and death in sub-groups with relatively poor SRH. Uchino et al. show that, not only is relatively poor SRH associated with increased levels of C-reactive protein, but also that a key mediator of this relationship was sleep quality (though not depression) which, they argue, is potentially amenable to intervention (Uchino et al., 2019). The gene discussed is CRP; the disease is major depressive disorder.