Moving beyond average values: assessing the night-to-night instability of sleep and arousal in DSM-IV-TR insomnia subtypes

• Published in: Sleep (New York, N.Y.) N.Y.), 2011-04, Vol.34 (4), p.531-539
• Main Authors: Sánchez-Ortuño, M Montserrat, Carney, Colleen E, Edinger, Jack D, Wyatt, James K, Harris, Andrea
• Format: Article
• Language: English
• Subjects: Arousal - physiology; Diagnostic and Statistical Manual of Mental Disorders; Female; Humans; Male; Mental Disorders - complications; Mental Disorders - physiopathology; Middle Aged; Night-to-Night Variability in Insomnia Subtypes; Polysomnography; Psychiatric Status Rating Scales; Severity of Illness Index; Sleep - physiology; Sleep Initiation and Maintenance Disorders - classification; Sleep Initiation and Maintenance Disorders - etiology; Sleep Initiation and Maintenance Disorders - physiopathology; Surveys and Questionnaires; Time Factors
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleep/34.4.531

We explored differences between individuals with DSM-IV-TR diagnoses of primary insomnia (PI) and insomnia related to a mental disorder (IMD) by using serial measurements of self-reported sleep variables (sleep onset latency, SOL; wake after sleep onset, WASO; total sleep time, TST; sleep efficiency, SE), and visual analogue scale ratings of 2 forms of bedtime arousal (cognitive and emotional). Furthermore, we sought to examine the relationship between sleep and arousal within each diagnostic subgroup. Between-group and within-group comparisons. Duke and Rush University Medical Centers, USA. One hundred eighty-seven insomnia sufferers (126 women, average age 47.15 years) diagnosed by sleep specialists at 2 sleep centers as PI patients (n=126) and IMD patients (n=61). N/A. Multilevel models for sleep measures indicated that IMD displayed significantly more instability across nights in their TST (i.e., larger changes) than did PI patients. With respect to pre-sleep arousal, IMD patients exhibited higher mean levels of emotional arousal, as well as more instability on the nightly ratings of this measure. Within the PI group, correlational analyses revealed a moderate relationship between the 2 arousal variables and SOL (r values 0.29 and 0.26), whereas the corresponding correlations were negligible and statistically nonsignificant in the IMD group. We found a number of differences on nighttime variables between those diagnosed with primary insomnia and those diagnosed with insomnia related to a mental disorder. These differences imply different perpetuating mechanisms involved in their ongoing sleep difficulties. Additionally, they support the categorical distinctiveness and the concurrent validity of these insomnia subtypes.