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Hypersomnia in bipolar depression: a comparison with narcolepsy using the multiple sleep latency test.
E A Nofzinger1, M E Thase, C F Reynolds
1Department of Psychiatry, University of Pittsburgh School of Medicine, PA.
The American Journal of Psychiatry
|September 1, 1991
Summary
Hypersomnia in bipolar depression may stem from anergia, not increased sleep need. This study found no REM sleep abnormalities in bipolar patients, unlike those with narcolepsy.
Area of Science:
- Neuroscience
- Sleep Medicine
- Psychiatry
Background:
- Hypersomnia is common in bipolar depression.
- Previous research suggested a link between hypersomnia and increased REM sleep.
- This study investigated the nature of hypersomnia in bipolar disorder.
Purpose of the Study:
- To objectively characterize hypersomnia in bipolar depression.
- To test the hypothesis that hypersomnia is linked to increased REM sleep.
- To compare sleep patterns in bipolar depression with narcolepsy.
Main Methods:
- Twenty-five hypersomnic bipolar depressed patients underwent polysomnography and a Multiple Sleep Latency Test (MSLT).
- Data were compared with 23 non-depressed narcoleptic patients.
- Nocturnal sleep and daytime nap data were analyzed.
Main Results:
- Bipolar patients showed no MSLT abnormalities despite hypersomnia complaints.
- REM sleep was absent during daytime naps in bipolar patients, contrasting with narcoleptic patients.
- No evidence supported increased sleep or REM sleep propensity in bipolar depression.
Conclusions:
- Sleepiness in bipolar depression is likely due to anergic symptoms like fatigue and psychomotor retardation.
- It is not associated with increased true sleep propensity or REM sleep propensity.
- Findings differentiate hypersomnia in bipolar depression from primary sleep disorders like narcolepsy.