The relationship between insomnia and health-related quality of life in patients with chronic illness

To determine the association between insomnia and health-related quality of life (HRQOL) in patients with chronic illness after accounting for the effects of depression, anxiety, and medical comorbidities. We used a cross-sectional analysis of Medical Outcomes Study (MOS) data. The sample consisted of 3445 patients who completed a self-administered questionnaire and who were given a diagnosis of 1 or more of 5 chronic medical and psychiatric conditions by an MOS clinician. Patients were recruited from the offices of clinicians practicing family medicine, internal medicine, endocrinology, cardiology, and psychiatry in 3 US cities. Outcomes were sleep items, health-related quality of life as measured by the Medical Outcomes Study Short Form Health Survey (SF-36), chronic medical comorbidity, depression, and anxiety. Insomnia was defined as the complaint of difficulty initiating or maintaining sleep. Insomnia was severe in 16% and mild in 34% of study patients. Patients with insomnia demonstrated significant global decrements in HRQOL. Differences between patients with mild insomnia versus no insomnia showed small to medium decrements across SF-36 subscales ranging from 4.1 to 9.3 points (on a scale of 0 to 100); the corresponding decrements for severe insomnia (versus no insomnia) ranged from 12.0 to 23.9 points. Insomnia is independently associated with worsened HRQOL to almost the same extent as chronic conditions such as congestive heart failure and clinical depression.