Interaction of Sleep and Cortical Structural Maintenance From an Individual Person Microlongitudinal Perspective and Implications for Precision Medicine Research

Abstract

Sleep and maintenance of brain structure are essential for the continuity of a person's cognitive/mental health. Interestingly, whether normal structural maintenance of the brain and sleep continuously interact in some way over day-week-month times has never been assessed at an individual-person level. This study used unconventional microlongitudinal sampling, structural magnetic resonance imaging, and n-of-1 analyses to assess normal interactions between fluctuations in the structural maintenance of cerebral cortical thickness and sleep duration for day, week, and multi-week intervals over a 6-month period in a healthy adult man. Correlation and time series analyses provided indications of "if-then," i.e., "if" this preceded "then" this followed, sleepto-thickness maintenance and thickness maintenance-to-sleep bidirectional inverse interactions. Inverse interaction patterns were characterized by concepts of graded influences across nights, bilaterally positive relationships, continuity across successive weeks, and longer delayed/prolonged effects in the thickness maintenance-to-sleep than sleep-to-thickness maintenance direction. These interactions are proposed to involve normal circadian/allostatic/homeostatic mechanisms that continuously influence, and are influenced by, cortical substrate remodeling/turnover and sleep/wake cycle. Understanding interactions of individual person "-omics" is becoming a central interest in precision medicine research. The present n-of-1 findings contribute to this interest and have implications for precision medicine research use of a person's cortical structural and sleep "-omics" to optimize the continuous maintenance of that individual's cortical structure, sleep, and cognitive/mental health.

Temporal Interactions between Maintenance of Cerebral Cortex Thickness and Physical Activity from an Individual Person Micro-Longitudinal Perspective and Implications for Precision Medicine

“…Details of the studied individual's medical history and health monitoring measures during the study have been published [8,9,13]. Salient points are briefly re-reviewed next.…”

“…Finally, his left and right hemisphere thickness means and ranges were encompassed within thickness measures reported in 11 recent investigations that defined normal adult hemispheric thicknesses with the Freesurfer procedures used in the present study [13].…”

“…This provided tests of relationships over a range of time scales and bracketing of periods that had graded degrees of relationships. This plan was used to successfully assess bidirectional temporal relationships between cortical thickness maintenance and sleep duration in this individual [13].…”

“…As previously reported [8,13] and briefly reviewed in Methods, the studied individual's medical history and daily health measures attested to his good health and fitness over life and during the study. Moreover, we have previously presented detailed comparisons which show that his hemispheric thickness mean and variation measures were encompassed within the range of hemispheric thickness mean and variation measures reported in 11 studies that applied FreeSurfer thickness measurement procedures in normal adult groups of his age and younger [13]. From this, his cortical thickness maintenance measures arguably fit normal expectations.…”

Causal associations between sleep traits and brain structure: a bidirectional Mendelian randomization study

“…Furthermore, longitudinal studies addressing this issue have been unable to elucidate the temporal sequence between sleep habits and brain IDPs, as sleep conditions or brain magnetic resonance imaging (MRI) were evaluated at only one time point [ 16 , 20 – 24 ]. Recently, the normal dynamics of bidirectional acute interaction between sleep duration and cortical thickness were revealed through microlongitudinal time series analyses based on data from one healthy individual [ 25 ]. However, no population-based longitudinal study or randomized controlled trial (RCT) has been published that can determine the bidirectional long-term causal relationships between sleep habits and brain structure.…”