title: Variability in Cumulative Habitual Sleep Duration Predicts Waking Functional Connectivity.
abstract: OBJECTIVE
  We examined whether interindividual differences in habitual sleep patterns, quantified as the cumulative habitual total sleep time (cTST) over a 2-w period, were reflected in waking measurements of intranetwork and internetwork functional connectivity (FC) between major nodes of three intrinsically connected networks (ICNs): default mode network (DMN), salience network (SN), and central executive network (CEN).
  
  
  METHODS
  Resting state functional magnetic resonance imaging (fMRI) study using seed-based FC analysis combined with 14-d wrist actigraphy, sleep diaries, and subjective questionnaires (N = 33 healthy adults, mean age 34.3, standard deviation ± 11.6 y). Data were statistically analyzed using multiple linear regression. Fourteen consecutive days of wrist actigraphy in participant's home environment and fMRI scanning on day 14 at the Birmingham University Imaging Centre. Seed-based FC analysis on ICNs from resting-state fMRI data and multiple linear regression analysis performed for each ICN seed and target. cTST was used to predict FC (controlling for age).
  
  
  RESULTS
  cTST was specific predictor of intranetwork FC when the mesial prefrontal cortex (MPFC) region of the DMN was used as a seed for FC, with a positive correlation between FC and cTST observed. No significant relationship between FC and cTST was seen for any pair of nodes not including the MPFC. Internetwork FC between the DMN (MPFC) and SN (right anterior insula) was also predicted by cTST, with a negative correlation observed between FC and cTST.
  
  
  CONCLUSIONS
  This study improves understanding of the relationship between intranetwork and internetwork functional connectivity of intrinsically connected networks (ICNs) in relation to habitual sleep quality and duration. The cumulative amount of sleep that participants achieved over a 14-d period was significantly predictive of intranetwork and inter-network functional connectivity of ICNs, an observation that may underlie the link between sleep status and cognitive performance.
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, Birmingham, UK.|Department of Neuropsychiatry, The Barberry National Centre for Mental Health, Birmingham, UK.
authors.forename: Sakh
authors.initials: S
authors.lastname: Khalsa
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, Birmingham, UK.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Mayhew
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, Birmingham, UK.
authors.forename: Izabela
authors.initials: I
authors.lastname: Przezdzik
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, Birmingham, UK.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Wilson
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, Birmingham, UK.
authors.forename: Joanne
authors.initials: J
authors.lastname: Hale
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, Birmingham, UK.
authors.forename: Aimee
authors.initials: A
authors.lastname: Goldstone
authors.affiliation: Department of Neuropsychiatry, The Barberry National Centre for Mental Health, Birmingham, UK.
authors.forename: Manny
authors.initials: M
authors.lastname: Bagary
authors.affiliation: Birmingham University Imaging Centre (BUIC), School of Psychology, University of Birmingham, Birmingham, UK.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Bagshaw
mesh_terms: D056044:Actigraphy; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000502:physiology; D003071:Cognition / Q000502:physiology; D005260:Female; D006184:Habits; D006262:Health; D006801:Humans; D016014:Linear Models; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000502:physiology*; D011996:Records; D012890:Sleep / Q000502:physiology*; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
keywords: DMN; central executive network; fMRI; functional connectivity; habitual total sleep time; salience network; sleep; sleep quality.