title: Clusters of Insomnia Disorder: An Exploratory Cluster Analysis of Objective Sleep Parameters Reveals Differences in Neurocognitive Functioning, Quantitative EEG, and Heart Rate Variability.
abstract: To empirically derive and evaluate potential clusters of Insomnia Disorder through cluster analysis from polysomnography (PSG). We hypothesized that clusters would differ on neurocognitive performance, sleep-onset measures of quantitative (q)-EEG and heart rate variability (HRV).
  
  
  
  Research volunteers with Insomnia Disorder (DSM-5) completed a neurocognitive assessment and overnight PSG measures of total sleep time (TST), wake time after sleep onset (WASO), and sleep onset latency (SOL) were used to determine clusters.
  
  
  
  From 96 volunteers with Insomnia Disorder, cluster analysis derived at least two clusters from objective sleep parameters: Insomnia with normal objective sleep duration (I-NSD: n = 53) and Insomnia with short sleep duration (I-SSD: n = 43). At sleep onset, differences in HRV between I-NSD and I-SSD clusters suggest attenuated parasympathetic activity in I-SSD (P < 0.05). Preliminary work suggested three clusters by retaining the I-NSD and splitting the I-SSD cluster into two: I-SSD A (n = 29): defined by high WASO and I-SSD B (n = 14): a second I-SSD cluster with high SOL and medium WASO. The I-SSD B cluster performed worse than I-SSD A and I-NSD for sustained attention (P ≤ 0.05). In an exploratory analysis,q-EEG revealed reduced spectral power also in I-SSD B before (Delta, Alpha, Beta-1) and after sleep-onset (Beta-2) compared to I-SSD A and I-NSD (P ≤ 0.05).
  
  
  
  Two insomnia clusters derived from cluster analysis differ in sleep onset HRV. Preliminary data suggest evidence for three clusters in insomnia with differences for sustained attention and sleep-onsetq-EEG.
  
  
  
  Insomnia 100 sleep study: Australia New Zealand Clinical Trials Registry (ANZCTR) identification number 12612000049875. URL: https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=347742.
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Medical School, University of Sydney, Australia.
authors: Christopher B
authors: CB
authors: Miller
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Medical School, University of Sydney, Australia.
authors: Delwyn J
authors: DJ
authors: Bartlett
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Nursing School, University of Sydney, Australia.
authors: Anna E
authors: AE
authors: Mullins
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Nursing School, University of Sydney, Australia.
authors: Kirsty L
authors: KL
authors: Dodds
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Nursing School, University of Sydney, Australia.
authors: Christopher J
authors: CJ
authors: Gordon
authors: Nuffield Department of Clinical Neurosciences and Sleep & Circadian Neuroscience Institute, University of Oxford, UK.
authors: Simon D
authors: SD
authors: Kyle
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.
authors: Jong Won
authors: JW
authors: Kim
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Medical School, University of Sydney, Australia.|Department of Respiratory and Sleep Medicine, RPAH, Sydney Local Health District, Sydney, NSW, Australia.
authors: Angela L
authors: AL
authors: D'Rozario
authors: Clinical Research Unit, Brain & Mind Centre, University of Sydney, Australia.
authors: Rico S C
authors: RS
authors: Lee
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.
authors: Maria
authors: M
authors: Comas
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Nursing School, University of Sydney, Australia.
authors: Nathaniel S
authors: NS
authors: Marshall
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Medical School, University of Sydney, Australia.|Department of Respiratory and Sleep Medicine, RPAH, Sydney Local Health District, Sydney, NSW, Australia.
authors: Brendon J
authors: BJ
authors: Yee
authors: Nuffield Department of Clinical Neurosciences and Sleep & Circadian Neuroscience Institute, University of Oxford, UK.
authors: Colin A
authors: CA
authors: Espie
authors: CIRUS, Centre for Sleep and Chronobiology, Woolcock Institute of Medical Research, University of Sydney, Australia.|Sydney Medical School, University of Sydney, Australia.|Department of Respiratory and Sleep Medicine, RPAH, Sydney Local Health District, Sydney, NSW, Australia.
authors: Ronald R
authors: RR
authors: Grunstein
mesh_terms: D000328:Adult; D000368:Aged; D001288:Attention / Q000502:physiology*; D001315:Australia; D016000:Cluster Analysis; D003071:Cognition / Q000502:physiology*; D004569:Electroencephalography; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D009520:New Zealand; D010641:Phenotype; D017286:Polysomnography; D012890:Sleep / Q000502:physiology; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis* / Q000503:physiopathology*; D013997:Time Factors
keywords: Insomnia Disorder; and phenotyping; cluster analysis; polysomnography; sleep