Insomnia Can Be Such a Pain: Prospective Associations of Incident Insomnia Disorder and Pain Conditions.

OBJECTIVE:Sleep disturbances and pain commonly co-occur, though the prospective relationship between diagnosable insomnia disorder and pain conditions remains unclear. Insomnia disorder is distinct from broader sleep disturbances; diagnostic criteria require longer symptom persistence and the presence of functional impairment, which may confer greater pain risk. The present study characterized directionality between incident insomnia disorder and incident pain conditions in a community sample. MATERIALS AND METHODS:This study assessed a large cohort (N = 2174) of US adults with no lifetime history of insomnia disorder, depression, or pain condition. Outcomes were assessed annually across two years. Insomnia disorder was classified using DSM-IV-TR criteria. Incident pain was defined as a newly reported diagnosis of back pain and/or chronic pain. Logistic regression models examined whether incident insomnia predicted incident pain conditions a year later and whether incident pain predicted incident insomnia disorder a year later. For descriptive purposes, post-hoc analyses explored pain severity and interference among pain patients by insomnia disorder status, and examined mediation analyses of depressive symptoms. RESULTS:Insomnia disorder predicted an incident pain condition one year later, odds ratio [OR] = 2.44, p = .02. Indeed, 10.8% of those with incident insomnia developed a pain condition one year later, compared to only 2.3% of those without insomnia. Pain patients with insomnia reported greater pain severity and greater pain interference than pain patients without insomnia, d = 0.67-1.07. Change in depressive symptoms significantly mediated the association between incident insomnia and later pain, indirect effect = 0.087, 95% CI [0.002,0.216]. Contrary to hypotheses, pain conditions did not predict future insomnia disorder, OR = 0.59, p = .61. CONCLUSION:Insomnia disorder is a robust risk factor for developing chronic pain and may represent a clinical target for pain prevention or early intervention. As pain patients with insomnia present with greater morbidity, addressing insomnia in pain interventions may enhance pain-related outcomes.