title: Sleep phenotypes of intellectual disability: a polysomnographic evaluation in subjects with Down syndrome and Fragile-X syndrome.
abstract: OBJECTIVE
  To analyze sleep architecture and NREM sleep alterations by means of the Cyclic Alternating Pattern (CAP) in children with Down syndrome (DS) and Fragile-X syndrome (fraX), the two most common causes of inherited mental retardation, in order to find out eventual alterations of their sleep microstructure related to their mental retardation phenotypes.
  
  
  METHODS
  Fourteen patients affected by fraX (mean age 13.1 years) and 9 affected by Down syndrome (mean age 13.8 years) and 26 age-matched normal controls were included. All subjects underwent overnight polysomnography in the sleep laboratory, after one adaptation night and their sleep architecture and CAP were visually scored.
  
  
  RESULTS
  FraX subjects showed a reduced time in bed compared to DS subjects, whereas DS subjects showed a lower sleep efficiency, a higher percentage of wakefulness after sleep onset, and a reduced percentage of stage 2 NREM compared to the other groups. Furthermore, DS and fraX subjects, compared to normal controls, showed a higher percentage of stage 1 NREM and a lower percentage of REM sleep. FraX subjects showed the most disrupted sleep microstructure with low total CAP rate and CAP rate in S2 NREM. Both patient groups showed a lower percentage of A1 and higher percentage of A2 and A3 compared to normal controls.
  
  
  CONCLUSIONS
  The analysis of CAP might be able to disclose new important findings in the sleep architecture of children with mental retardation and might characterize sleep microstructural patterns of the different phenotypes of intellectual disability.
  
  
  CONCLUSIONS
  The NREM sleep microstructure alterations found in our subjects, associated with the reduction in REM sleep percentage, seem to be distinctive features of intellectual disability.
authors.affiliation: Department of Pediatrics, Sleep Centre, "La Sapienza" University, S. Andrea Hospital, Rome, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Miano
authors.forename: Oliviero
authors.initials: O
authors.lastname: Bruni
authors.forename: Maurizio
authors.initials: M
authors.lastname: Elia
authors.forename: Lidia
authors.initials: L
authors.lastname: Scifo
authors.forename: Arianna
authors.initials: A
authors.lastname: Smerieri
authors.forename: Alessia
authors.initials: A
authors.lastname: Trovato
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Verrillo
authors.forename: Mario G
authors.initials: MG
authors.lastname: Terzano
authors.forename: Raffaele
authors.initials: R
authors.lastname: Ferri
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D004314:Down Syndrome / Q000150:complications*; D004569:Electroencephalography / Q000379:methods; D005260:Female; D005600:Fragile X Syndrome / Q000150:complications*; D006801:Humans; D008297:Male; D010641:Phenotype; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*; D012893:Sleep Wake Disorders / Q000209:etiology*; D018709:Statistics, Nonparametric