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

OBJECTIVES: 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.

STUDY DESIGN: We used a cross-sectional analysis of Medical Outcomes Study (MOS) data.

POPULATION: 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 MEASURED: 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.

RESULTS: 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.

CONCLUSIONS: Insomnia is independently associated with worsened HRQOL to almost the same extent as chronic conditions such as congestive heart failure and clinical depression.