Sleep spindles in chronic psychophysiological insomnia.
OBJECTIVE
A sleep spindle is an electroencephalographic feature that is unique to sleep. It has been suggested that this phasic event has a sleep-protective function. The objective of the present study was to document one aspect of sleep protection in chronic insomnia sufferers: the number and density of sleep spindles in Stage 2 sleep.


METHODS
Sleep spindles were scored during Stage 2 sleep on the second and third nights of a protocol of polysomnographic recordings that lasted for four consecutive nights. The sample included 16 participants suffering from insomnia (INS group; mean age=43.4 years) and 14 good sleepers (GS group; mean age=38.1 years). Participants underwent sleep and psychological evaluations. The INS group participants met the diagnostic criteria for primary psychophysiological insomnia (mean duration of insomnia=9.6 years).


RESULTS
The total number of sleep spindles in Stage 2 sleep and the density (sleep spindles per minute) according to the total time spent in Stage 2 sleep were compiled. Repeated-measures analyses of variance showed no significant difference in the number and in the density of sleep spindles between the INS group (68.46 and 0.60, respectively) and the GS group (56.28 and 0.46, respectively).


CONCLUSIONS
These results suggest no deficiency in the sleep-protection mechanism of psychophysiological insomnia sufferers in comparison with good sleeper controls, as measured by the number and density of sleep spindles.
Bastien
Célyne H
CH
Ecole de Psychologie, Université Laval, Québec, Canada G1V 0A6. celyne.bastien@psy.ulaval.ca
St-Jean
Geneviève
G
Turcotte
Isabelle
I
Morin
Charles M
CM
Lavallée
Mélanie
M
Carrier
Julie
J
D000328:Adult; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012016:Reference Values; D012815:Signal Processing, Computer-Assisted; D007319:Sleep Initiation and Maintenance Disorders / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D012894:Sleep Stages / Q000502:physiology