Nature and Science of Sleep (Aug 2022)
Nighttime Sleep Characteristics and White Matter Integrity in Young Adults
Abstract
Sussanne Reyes,1 Carolina de Medeiros Rimkus,2 Betsy Lozoff,3 Cecilia Algarin,1 Patricio Peirano1 1Laboratory of Sleep and Functional Neurobiology, Institute of Nutrition and Food Technology (INTA), University of Chile, Santiago, Chile; 2Laboratory of Medical Investigation (LIM-44), Department of Radiology and Oncology, Faculty of Medicine, University of Sao Paulo, São Paulo, São Paulo, Brazil; 3Department of Pediatrics and Environmental Health Sciences, University of Michigan, Ann Arbor, MI, USACorrespondence: Patricio Peirano, Laboratory of Sleep and Functional Neurobiology, Institute of Nutrition and Food Technology (INTA), University of Chile, El Líbano 5524, Macul 7830490, Región Metropolitana, Santiago, Chile, Tel +56 2 29781447, Email [email protected]: Sleep is essential for life and plays a key role for optimal physiology, brain functioning, and health. Evidence suggests a relation between sleep and cerebral white matter integrity. Human studies report that sleep duration shows a U-shaped association with brain functioning. We hypothesized that participants with longer or shorter sleep time in the nighttime period show altered microstructural white matter integrity.Participants and Methods: Seventy-three young adult participants were evaluated. Sleep-wake cycle parameters were assessed objectively using actigraphy. Diffusion tensor imaging studies were performed to assess white matter integrity using fractional anisotropy and mean, axial, and radial diffusivities. Relations between white matter microstructure indexes and sleep parameters were investigated through tract-based spatial statistics. Participants were grouped according to their nocturnal total sleep time: 27 in the Reference sleep group (6.5– 8.0 h), 23 in the Short sleep group ( 8.0 h).Results: Compared with the Reference sleep group, participants in the Long sleep group showed lower fractional anisotropy (p < 0.05) and higher radial diffusivity (p < 0.05) values in white matter tracts linked to sleep regulation (corona radiata, body of the corpus callosum, superior longitudinal fasciculus, and anterior thalamic radiation).Conclusion: This pattern of reduced fractional anisotropy and increased radial diffusivity in the Long sleep group indicates an association between sleep duration and lower integrity of myelin sheaths. Because myelin is continuously remodeled in the brain, nighttime sleep characteristics appear to be a key player for its quality and maintenance.Keywords: long sleep, brain, myelin, fractional anisotropy
