Depression and excessive sleep
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Prevalence and Risk Factors: Depression and Excessive Sleep
Excessive sleep, including excessive daytime sleepiness (EDS) and long nighttime sleep, is common among people with depression. Studies show that about half of individuals with major depression experience EDS, and this symptom is linked to several risk factors such as higher body mass index, younger age, higher depression severity, atypical depression, and the use of certain antidepressants like SSRIs and SNRIs. Sleep apnea and inflammation (measured by C-reactive protein) are also associated with EDS in depression 1. Hypersomnia is present in about 40% of young depressed adults and 10% of older patients, with a higher prevalence in females 7.
Sleep Duration and Depression: U-Shaped Relationship
Research consistently finds a U-shaped relationship between sleep duration and depression risk. Both short sleep (less than 6 hours) and long sleep (more than 8 hours) are associated with a higher risk of depression. Daytime napping for more than one hour and snoring further increase this risk, and these factors can have a combined effect 510. This pattern is seen in both general and rural populations, as well as in large national samples 510.
Impact on Daily Well-Being and Symptom Severity
Depressed adults experience greater fluctuations in mood depending on how much they sleep. Both too little and too much sleep are linked to worse daily mood, with more negative feelings and less positive affect. These effects are much stronger in people with depression compared to those without depression 6. Excessive sleepiness and insomnia together are associated with more severe depression, including higher suicidal ideation, greater seasonal mood changes, and disruptions in daily activity and social life 2.
Sleep Disturbances as Predictors and Core Symptoms
Sleep disturbances, including EDS and insomnia, are not only symptoms of depression but also risk factors for developing depression in the future. In adolescents, sleep problems predict higher depression scores one year later, especially in girls 4. In adults, both insomnia and EDS are linked to higher overall, cognitive, and somatic depressive symptoms 3. These sleep issues often persist even after depression treatment and increase the risk of relapse 7.
Biological and Clinical Considerations
Depression is associated with changes in sleep architecture, such as increased REM sleep and disrupted sleep continuity. These changes can be measured objectively and may serve as biomarkers for depression diagnosis and treatment response 8. In some cases, EDS in depression overlaps with conditions like obstructive sleep apnea, and treating sleep apnea can improve both sleepiness and depressive symptoms 9.
Conclusion
Excessive sleep and sleepiness are closely linked to depression, both as symptoms and as risk factors. The relationship is complex, with both too little and too much sleep increasing depression risk and affecting daily mood. Addressing sleep disturbances is important for managing depression, improving quality of life, and reducing the risk of relapse.
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