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Abstract Introduction Insomnia is diagnosed based on subjective difficulty falling asleep, staying asleep, and early morning awakenings. Evidence of objective EEG abnormalities is mixed, in part due to small sample sizes and variable definitions of insomnia. This study aimed to explore these issues by comparing the insomnia case group and the control group on sleep physiology objectively measured depending on separate qualitative and quantitative self-reported insomnia symptoms. Methods Analyses are based on questionnaires and PSG data from the Sleep Apnea Global Interdisciplinary Consortium (SAGIC). Two distinct insomnia case groups were defined. A qualitative insomnia case was defined as self-reported difficulty falling or staying asleep at least 3 nights/week for more than 3 months and moderate or greater impairment in daytime function due to poor sleep (n=350, 58% female; 48.47±14.38 years). The quantitative case definition required average self-reported sleep latency or wakefulness after sleep onset 30 minutes combined with the frequency and impairment criteria. (n=196, 62% female; 48.77±13.74 years). We also defined control groups without insomnia. Participants were excluded if they had sleep apnea (apnea-hypopnea index AHI 5 events/hour) or were shift workers. Multivariate analysis of variance (MANOVA) models, adjusted for age and sex, were separately conducted to compare the insomnia and control groups. The focus was on traditional sleep architecture variables, EEG power within specific frequency bands, and odds ratio product (ORP, representing sleep depth) metrics. Results The MANOVA analysis indicated significant group differences, with post-hoc tests identifying key variables responsible for these distinctions. In qualitative criteria, sleep onset latency, sigma, beta1, and beta2 in EEG1 and EEG2, along with REM and NREM ORP, were significant contributors to the observed differences. In quantitative criteria, besides the same result in qualitative criteria, REM stage and alpha in EEG1 and EEG2 played significant roles. Effect sizes were consistent across both qualitative and quantitative criteria. Conclusion While the analyses depending on qualitative and quantitative criteria did not have different effect sizes, some variables contributed to the group differences. As such, the results of this study support the idea that qualitative and quantitative criteria measure the same dimensions for physiological differences related to insomnia. Support (if any)
Lee et al. (Sat,) studied this question.