Predictors of Daytime Consequences of Insomnia: The Roles of Quantitative Criteria and Nonrestorative Sleep

Background: The implications of removing nonrestorative sleep (NRS) and adding quantitative criteria in the most recent diagnostic criteria of insomnia disorder remain unresolved. The study was aimed to investigate how nighttime quantitative measures of sleep quality and NRS relate to daytime functioning in a general population sample. Sampling and Methods: Data of 905 subjects (mean age = 47.0 years; 64.5% females) in a population-based survey who had insomnia symptoms or NRS at least 1 night in a typical week were analyzed to evaluate their relationship with "functional impairment," "concerns/distress," and "interference with daily activities" over the past 30 days. Receiver-operating characteristic curve analysis was performed, while controlling for age and gender. Results: Moderate to severe NRS was the first-level predictor of all 3 daytime variables. Insomnia frequency ≥3 times per week and sleep onset latency ≥10-20 min were second-level predictors. Conclusions: We found that NRS was more important than insomnia symptoms in determining daytime consequences of insomnia. On the basis of our findings we express concerns whether the removal of NRS from the most recent diagnostic criteria may lead to its underrecognition, but support the quantitative criteria on insomnia frequency of at least 3 nights per week.