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Updated: May 9, 2026

Association Between Sleep Quality and Cognitive Symptoms in Patients with Major Depressive Disorder
Published on: April 26, 2024
Excessive sleep duration and quality of life
Maurice M Ohayon1, Charles F Reynolds, Yves Dauvilliers
1Stanford Sleep Epidemiology Research Center, Stanford University School of Medicine, Palo Alto, CA 94303, USA. mohayon@stanford.edu
Objective:
Using population-based data, we document the comorbidities (medical, neurologic, and psychiatric) and consequences for daily functioning of excessive quantity of sleep (EQS), defined as a main sleep period or 24-hour sleep duration ≥ 9 hours accompanied by complaints of impaired functioning or distress due to excessive sleep, and its links to excessive sleepiness.
Methods:
A cross-sectional telephone study using a representative sample of 19,136 noninstitutionalized individuals living in the United States, aged ≥ 18 years (participation rate = 83.2%). The Sleep-EVAL expert system administered questions on life and sleeping habits; health; and sleep, mental, and organic disorders (Diagnostic and Statistical Manual of Mental Disorders, 4th edition, text revision; International Classification of Sleep Disorders: Diagnostic and Coding Manual II, International Classification of Diseases and Related Health Problems, 10th edition).
Results:
Sleeping at least 9 hours per 24-hour period was reported by 8.4% (95% confidence interval = 8.0-8.8%) of participants; EQS (prolonged sleep episode with distress/impairment) was observed in 1.6% (1.4-1.8%) of the sample. The likelihood of EQS was 3 to 12× higher among individuals with a mood disorder. EQS individuals were 2 to 4× more likely to report poor quality of life than non-EQS individuals as well as interference with socioprofessional activities and relationships. Although between 33 and 66% of individuals with prolonged sleep perceived it as a major problem, only 6.3 to 27.5% of them reported having sought medical attention.
Interpretation:
EQS is widespread in the general population, co-occurring with a broad spectrum of sleep, medical, neurologic, and psychiatric disorders. Therefore, physicians must recognize EQS as a mixed clinical entity indicating careful assessment and specific treatment planning.
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