Last update:
17-Sep-2004

OBJECTIVE Psychophysiological abnormalities indicative of hyperarousal have been observed in insomniacs leading to the hypothesis that primary insomnia is the result of a disorder of a 24-hour/day excessive arousal. The aim of this study was to test this hypothesis.

METHOD Psychophysiological differences between 16 patients with primary insomnia according to DSM-IV and 16 controls (matched for age, sex and education) were assessed through all-night polysomnography and the Multiple Sleep Latency Tests (MSLT) performed during the day. The Athens Insomnia Scale (AIS) and the Hyperarousal Scale (HS) were utilized to assess subjective severity of insomnia and hyperarousal, respectively. Motor activity was recorded continuously for seven days through wrist actigraphs, and daytime functioning was assessed based on the Selective Reminding Test (SRT) and the Continuous Attention Test (CAT).

RESULTS In the patient's group motor activity level was found higher during the night, sleep efficiency lower, and the EEG desynchronisation in slow wave sleep was higher. Diurnal measures of arousal were found also to be increased in the patients. The score on the HS was higher in insomniacs than in the controls and it was significantly correlated with the severity of insomnia evaluated with the AIS. Sleep latency in all MSLT sessions was no shorter in patients despite their non-satisfying sleep at night. Impaired daytime functioning in insomniacs was confirmed, as the number of presentations necessary to memorize all items of the SRT was greater in the patient group than in the control group. Further, the degree of learning disturbance correlated with insomnia severity as scored on the AIS. No correlation between the SRT and polysomnographic parameters were observed.

CONCLUSIONS (a) A 24-hour increase of arousal is confirmed in primary insomnia, (b) poor sleep alone is not the basis of complaints of impaired daytime functioning among insomniacs, (c) the Athens Insomnia Scale is a sensitive clinical tool which can be used to improve the description of insomnia populations.

Key words: Cag-A, Congenital hemorrhagic disorders, Gastrointestinal hemorrhage.