title: Human sleep spindle characteristics after sleep deprivation.
abstract: OBJECTIVE
  Sleep spindles (12-15 Hz oscillations) are one of the hallmarks of the electroencephalogram (EEG) during human non-rapid eye movement (non-REM) sleep. The effect of a 40 h sleep deprivation (SD) on spindle characteristics along the antero-posterior axis was investigated.
  
  
  METHODS
  EEGs during non-REM sleep in healthy young volunteers were analyzed with a new method for instantaneous spectral analysis, based on the fast time frequency transform (FTFT), which yields high-resolution spindle parameters in the combined time and frequency domain.
  
  
  RESULTS
  FTFT revealed that after SD, mean spindle amplitude was enhanced, while spindle density was reduced. The reduction in spindle density was most prominent in the frontal derivation (Fz), while spindle amplitude was increased in all derivations except in Fz. Mean spindle frequency and its variability within a spindle were reduced after SD. When analyzed per 0.25 Hz frequency bin, amplitude was increased in the lower spindle frequency range (12-13.75 Hz), whereas density was reduced in the high spindle frequency range (13.5-14.75 Hz).
  
  
  CONCLUSIONS
  The observed reduction in spindle density after SD confirms the inverse homeostatic relationship between sleep spindles and slow waves whereas the increase in spindle amplitude and the reduction in intra-spindle frequency variability support the hypothesis of a higher level of synchronization in thalamocortical cells when homeostatic sleep pressure is enhanced.
authors.affiliation: Centre for Chronobiology, Psychiatric University Clinic, Wilhelm Klein-Str. 27, CH-4025 Basel, Switzerland.
authors.forename: Vera
authors.initials: V
authors.lastname: Knoblauch
authors.forename: Wim L J
authors.initials: WL
authors.lastname: Martens
authors.forename: Anna
authors.initials: A
authors.lastname: Wirz-Justice
authors.forename: Christian
authors.initials: C
authors.lastname: Cajochen
mesh_terms: D000328:Adult; D004569:Electroencephalography; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D010507:Periodicity; D012892:Sleep Deprivation / Q000503:physiopathology*; D012894:Sleep Stages / Q000502:physiology*