Cross-sectional analyses of factors associated with the presence and aggravation of chronic insomnia by symptom subtypes

AimThe aim of this study was to investigate the association of psychological and chronobiological factors with the presence and severity of chronic insomnia by symptom subtypes and their impacts on daytime dysfunctions.MethodsParticipants of the present web-based epidemiological study were classified as follows: difficulty initiating sleep (DIS) (n = 91); difficulty maintaining sleep (DMS) (n = 13); early morning awakening (EMA) (n = 48); DIS + DMS (n = 67); DIS + EMA (n = 23); DMS + EMA (n = 24); triplet of DIS, DMS, and EMA symptoms (TRP) (n = 69); and normal sleepers (n = 4590). The Insomnia Severity Index (ISI), Hospital Anxiety and Depression Scale (HADS), Munich Chronotype Questionnaire (MCTQ), insomnia-related psychological measures (including the Ford Insomnia Response to Stress Test [FIRST] and the Dysfunctional Beliefs and Attitudes about Sleep Scale [DBAS]), and the cognitive and somatic domains of the Pre-Sleep Arousal Scale (PSAS) were evaluated.ResultsThe presence of DIS and DIS + DMS were significantly associated with an evening preference, and EMA and EMA + DMS with a morning preference, while TRP showed no significant association with either chronotype. The increase in DBAS scores was associated with higher ISI scores in all subtypes. Meanwhile, the associations of each psychological measure varied among insomnia subtypes, with the association of PSAS cognitive arousal to DIS and PSAS somatic arousal to both DMS + EMA and TRP. Pathological HADS score was associated with all subtypes.ConclusionChronotypes may be associated with the presence of some insomnia subtypes; however, only psychological factors were speculated to contribute to the aggravation of all subtypes. All insomnia subtypes possibly contribute to the formation of depression. Subtypes including difficulty initiating sleep (DIS) tended to be evening preference, while those including early morning awakening (EMA) tended to be morning preference. There was no chronotypic tendency in the group including all subtypes or the group including DIS and EMA. The psychological factors associated with each subtype differed; DIS was significantly associated with PSAS cognitive arousal and TRP with PSAS somatic arousal, indicating that the psychological factors associated with each subtype differed. image