Spontaneous K-complexes in chronic psychophysiological insomnia

• Published in: Journal of psychosomatic research 2009-08, Vol.67 (2), p.117-125
• Main Authors: Bastien, Célyne H, St-Jean, Geneviève, Turcotte, Isabelle, Morin, Charles M, Lavallée, Mélanie, Carrier, Julie, Forget, Daniel
• Format: Article
• Language: English
• Subjects: Adult; Chronic Disease; Chronic insomnia; Electroencephalography; Female; Humans; Insomnia; K-complex; Male; Polysomnography; Psychiatry; Psychophysiological aspects; Severity of Illness Index; Sleep Initiation and Maintenance Disorders - diagnosis; Sleep Initiation and Maintenance Disorders - physiopathology; Sleep Initiation and Maintenance Disorders - psychology; Sleep Stages - physiology; Sleep-protective mechanisms; Suffering; Surveys and Questionnaires
• ISSN: 0022-3999; 1879-1360
• DOI: 10.1016/j.jpsychores.2009.01.014

Abstract Objective Spontaneous K-complexes are electroencephalographic features unique to non-rapid eye movement sleep. It has been suggested that this phasic event is a sleep-protective mechanism. Because insomnia sufferers report poor sleep quantity and quality, the objective of this study was to document the occurrence of spontaneous K-complexes in Stage 2 sleep of individuals with chronic insomnia. Specifically, the number and density of spontaneous K-complexes were studied in psychophysiological insomnia sufferers. Setting This study took place in a sleep and event-related potentials laboratory. Design Spontaneous K-complexes were scored during Stage 2 sleep on the second and third nights of a four-consecutive-nights protocol of polysomnographic recordings. Participants The sample included 14 participants suffering from psychophysiological insomnia (INS group; mean age=44.1 years) and 14 good sleepers (mean age=38.1 years). Participants underwent sleep and psychological evaluations. INS group participants met the diagnostic criteria for primary psychophysiological insomnia (mean duration of insomnia=9.6 years). Intervention Not applicable. Results The total number of spontaneous K-complexes and the density according to the total time spent in Stage 2 sleep (spontaneous K-complexes per minute) were compiled. Repeated-measures analyses of variance showed no significant difference in the number and density of spontaneous K-complexes between the INS group (313.98 and 2.66) and the GS group (361.10 and 2.88), respectively. Conclusion These results suggest no deficiency in the sleep-protective mechanism of psychophysiological insomnia sufferers in comparison with good sleepers, as measured by the spontaneous K-complexes' number and density.