Identifying major life events associated with insomnia disorder: Stressors that disrupt safety, stability, and...

Major life stress is a well-established precipitating factor for insomnia disorder. However, not all stressors are equally harmful, and determining which events pose the greatest risk to sleep is not well-understood. Identifying high-impact stressors on insomnia will deepen our understanding of how this disorder develops, particularly among those most vulnerable to insomnia. The present study explored a wide range of major life events to identify which stressors were associated with incident insomnia disorder.

This study assessed a large cohort (N = 2887) of U.S. adults across three timepoints: baseline, 1-year follow-up, and 2-year follow-up. Mixed-effects logistic regression was used to explore the association of major life events (Social Readjustment Rating Scale) with DSM-IV-TR insomnia disorder classification, controlling for sociodemographic factors. Differences by sleep reactivity (Ford Insomnia Response to Stress Test) were examined post hoc.

Fifteen major life stressors significantly predicted incident insomnia disorder. Key triggers included interpersonal stressors (e.g., infidelity, exposure to violence), work stressors (e.g., job loss, losing health benefits), home stressors (e.g., financial difficulties), and major injury/illness to oneself or close family member. The highest rates of insomnia onset were reported by highly reactive sleepers faced with major life stress (≥19%), whereas the lowest rates of insomnia were reported by low-reactive sleepers unexposed to major stress (≈5%).

Major stressors were most harmful when they threatened an individual's stability, safety, and core identity. Highly reactive sleepers may experience high levels of sustained hyperarousal when exposed to these high-impact stressors, thereby increasing the risk of insomnia disorder.