Naps Reliably Estimate Nocturnal Sleep Spindle Density in Health and Schizophrenia
Received: 25 August 2019 | Revised: 21 November 2019 | Accepted: 23 November 2019 DOI: 10.1111/jsr.12968 SHORT PAPER Naps reliably estimate nocturnal sleep spindle density in health and schizophrenia Dimitrios Mylonas1,2,3 | Catherine Tocci1 | William G. Coon1,2,3 | Bengi Baran1,2,3 | Erin J. Kohnke1 | Lin Zhu1 | Mark G. Vangel4,5 | Robert Stickgold3,6 | Dara S. Manoach1,2,3 1Department of Psychiatry, Massachusetts General Hospital, Charlestown, MA, USA Abstract 2Athinoula A. Martinos Center for Sleep spindles, defining oscillations of non-rapid eye movement stage 2 sleep (N2), Biomedical Imaging, Charlestown, MA, USA mediate memory consolidation. Spindle density (spindles/minute) is a stable, herit- 3Harvard Medical School, Boston, MA, USA able feature of the sleep electroencephalogram. In schizophrenia, reduced spindle 4Department of Radiology, Massachussets General Hospital, Charlestown, MA, USA density correlates with impaired sleep-dependent memory consolidation and is a 5Department of Biostatistics, Harvard promising treatment target. Measuring sleep spindles is also important for basic stud- Medical School, Boston, MA, USA ies of memory. However, overnight sleep studies are expensive, time consuming and 6Department of Psychiatry, Beth Israel Deaconess Medical Center, Boston, MA, require considerable infrastructure. Here we investigated whether afternoon naps USA can reliably and accurately estimate nocturnal spindle density in health and schizo- Correspondence phrenia. Fourteen schizophrenia patients and eight healthy controls had polysom- Dimitrios Mylonas, Department of nography during two overnights and three afternoon naps. Although spindle density Psychiatry, Massachusetts General Hospital, 149 13th Street, Charlestown, MA 02129, was lower during naps than nights, the two measures were highly correlated. For USA. both groups, naps and nights provided highly reliable estimates of spindle density.
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