Sleep spindle activity is correlated with reading abilities in developmental dyslexia.
OBJECTIVE
To analyze sleep architecture of children with dyslexia, by means of conventional parameters and EEG spectral analysis and to correlate sleep parameters and EEG spectra with neuropsychological measures.


METHODS
Cross-sectional study involving validated sleep questionnaires, neuropsychological scales, and polysomnographic recordings.


METHODS
Sleep laboratory in academic center.


METHODS
Sixteen subjects with developmental dyslexia (mean age 10.8 years) and 11 normally reading children (mean age 10.1 years). All the subjects underwent overnight polysomnographic recording; EEG power spectra were computed from the Cz derivation and spindle density was calculated during sleep stages N2.


METHODS
N/A.


RESULTS
Dyslexic children showed an increase in power of frequency bands between 0.5-3 Hz and 11-12 Hz in stage N2 and between 0.5-1 Hz in stage N3; they also showed significantly increased spindle density during N2. The power of the sigma band in N2 was positively correlated with the Word reading and MT reading tests; similarly, spindle density was significantly correlated with the Word reading test. The increased spindle activity and EEG sigma power in dyslexic subjects were found to be correlated with the degree of dyslexic impairment.


CONCLUSIONS
The correlation found between sleep spindle activity and reading abilities in developmental dyslexia supports the hypothesis of a role for NREM sleep and spindles in sleep-related neurocognitive processing.
Bruni
Oliviero
O
Center for Pediatric Sleep Disorders, Department of Developmental Neurology and Psychiatry, Sapienza University, Rome, Italy. oliviero.bruni@uniroma1.it
Ferri
Raffaele
R
Novelli
Luana
L
Terribili
Monica
M
Troianiello
Miriam
M
Finotti
Elena
E
Leuzzi
Vincenzo
V
Curatolo
Paolo
P
D000293:Adolescent; D002648:Child; D003430:Cross-Sectional Studies; D004410:Dyslexia / Q000150:complications*; D004569:Electroencephalography / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D017286:Polysomnography / Q000379:methods / Q000706:statistics & numerical data; D011932:Reading; D012894:Sleep Stages; D012893:Sleep Wake Disorders / Q000150:complications* / Q000175:diagnosis; D011795:Surveys and Questionnaires; D014888:Wechsler Scales / Q000706:statistics & numerical data