Gray Matter Volume Correlates of Sleepiness: A Voxel-Based Morphometry Study in Younger and Older Adults
Received 9 February 2020
Accepted for publication 14 April 2020
Published 21 May 2020 Volume 2020:12 Pages 289—298
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Professor Steven A Shea
Torbjörn Åkerstedt,1,2 Mats Lekander,1,2 Gustav Nilsonne,1,2 Sandra Tamm,1,2 Paolo d’Onofrio,1,2 Göran Kecklund,1,2 Håkan Fischer,3 Johanna Schwarz,1,2 Predrag Petrovic,1 Kristoffer NT Månsson4– 6
1Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; 2Stress Research Institute, Department of Psychology, Stockholm University, Stockholm, Sweden; 3Department of Psychology, Stockholm University, Stockholm, Sweden; 4Centre for Psychiatry Research, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; 5Center for Lifespan Psychology, Max Planck Institute for Human Development, Berlin, Germany; 6Max Planck UCL Centre for Computational Psychiatry and Ageing Research, Berlin, Germany
Correspondence: Torbjörn Åkerstedt
Department of Clinical Neuroscience, Karolinska Institutet, Stockholm 17177, Sweden
Background: Subjectively experienced sleepiness is a problem in society, possibly linked with gray matter (GM) volume. Given a different sleep pattern, aging may affect such associations, possibly due to shrinking brain volume.
Purpose: The purpose of the present study was to investigate the association between subjectively rated sleepiness and GM volume in thalamus, insula, hippocampus, and orbitofrontal cortex of young and older adults, after a normal night’s sleep.
Methods: Eighty-four healthy individuals participated (46 aged 20– 30 years, and 38 aged 65– 75 years). Morphological brain data were collected in a 3T magnetic resonance imaging (MRI) scanner. Sleepiness was rated multiple times during the imaging sessions.
Results: In older, relative to younger, adults, clusters within bilateral mid-anterior insular cortex and right thalamus were negatively associated with sleepiness. Adjustment for the immediately preceding total sleep time eliminated the significant associations.
Conclusion: Self-rated momentary sleepiness in a monotonous situation appears to be negatively associated with GM volume in clusters within both thalamus and insula in older individuals, and total sleep time seems to play a role in this association. Possibly, this suggests that larger GM volume in these clusters may be protective against sleepiness in older individuals. This notion needs confirmation in further studies.
Keywords: brain imaging, thalamus, insula, sleep, KSS
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