What causes persistent insomnia in adults?

Persistent insomnia is a common and consequential health problem that affects daily functioning, mental health, and long-term physical risk. Daniel J. Buysse at the University of Pittsburgh emphasizes that when difficulty falling or staying asleep persists for months and produces daytime impairment, it moves beyond an acute stress response into a chronic disorder requiring clinical attention. Prevalence estimates from sleep medicine research indicate that a substantial minority of adults experience chronic insomnia, making its causes and consequences important for clinicians, employers, and communities.

Biological and psychiatric causes

Biological predisposition and sustained physiological hyperarousal are central mechanisms. Charles M. Morin at Université Laval describes a tendency in some people toward heightened cognitive and somatic arousal at night, which perpetuates sleeplessness even after the initial trigger resolves. Psychiatric disorders are frequent contributors: major depressive disorder and generalized anxiety disorder commonly coexist with insomnia and can both precipitate and maintain disrupted sleep. Chronic medical conditions such as persistent pain, respiratory disease, endocrine disorders, and neurological conditions interfere with sleep continuity through symptoms and medications. Certain prescription and over-the-counter drugs, stimulants, and alcohol use alter sleep architecture and can create dependence on substances that fragment sleep. Genetic and age-related changes in sleep regulation also increase vulnerability, which helps explain higher rates of insomnia among older adults.

Circadian, environmental, and social contributors

Circadian misalignment produced by shift work, transmeridian travel, or irregular social schedules contributes to persistent insomnia. Charles A. Czeisler at Harvard Medical School has detailed how misaligned internal clocks lead to difficulty initiating sleep at socially expected times and to reduced sleep quality. Environmental factors such as urban light pollution, nighttime noise, and inadequate housing conditions worsen sleep and disproportionately affect low-income and densely populated territories. Cultural expectations around productivity, caregiving roles, and stigma toward reporting sleep problems shape who seeks help; in many societies women report greater insomnia because of disproportionate caregiving responsibilities and hormonal transitions. Migration, displacement, and occupational patterns in particular regions can create community-level sleep disruptions that sustain insomnia across households.

Consequences and clinical relevance

Persistent insomnia carries significant consequences for mood, cognition, occupational safety, and chronic disease risk. Research summarized by sleep medicine experts links long-term insomnia to increased likelihood of depressive episodes, impaired attention and memory, and higher rates of motor vehicle and workplace accidents. There is also evidence connecting chronic sleep disturbance to elevated cardiometabolic risk, which highlights insomnia as a public health concern beyond individual suffering. Clinically, identification of comorbid psychiatric or medical drivers and attention to social and environmental context guide effective management. Colleen E. Carney at Toronto Metropolitan University has advocated for cognitive behavioral approaches tailored to the individual’s biopsychosocial profile, reflecting the consensus that treating underlying causes and modifying environmental contributors yields the best outcomes.