Fig. 2.

The difference between three groups. a ~ i were analyzed by non-parametric analysis and j ~ k by parametric test. HC, healthy control; ISSD, insomnia with objective short sleep duration; INSD, insomnia with objective normal sleep duration; PSQI, Pittsburg Sleep Quality Index; PSQI-TST, Subjective Total Sleep Duration reported by PSQI’s item 4; ISI, Insomnia Severity Index; PSAS, Pre-sleep arousal scale; SA, Somatic arousal; CA, Cognitive arousal; TST, Total Sleep Duration; SL, Sleep Latency; WT, Wakefulness Time, LST, Light Sleep Time; DST, Deep Sleep Time. ^*p < 0.05; ^**p < 0.01; ^***p < 0.001. All p-values are Kruskal–Wallis H test with Dunn post-test