Study objective: Establishing quantitative criteria to distinguish individuals with and without insomnia is important for clinical and research applications, but consensus has not yet been reached for specific values. The purpose of this study was to identify the optimal quantitative thresholds for actigraphy and sleep diary that differentiate older adults (> 60 years) with insomnia from good sleeper controls.
Methods: A total of 119 participants (79 insomnia [35% male], 40 control [31.7% male]; mean age = 71.7 [7.2] years) completed at least 7 nights of sleep diary and actigraphy. Receiver operating characteristic curve analyses and the Youden index were used to identify optimal threshold values. Outcomes for each measurement method included sleep onset latency (SOL), wake time after sleep onset (WASO), sleep efficiency (SE), and total sleep time (TST).
Results: Sleep diary measures produced areas under the curves (AUC) in the high range (0.84-0.97), whereas actigraphy performed poorly at discriminating the two groups (AUC 0.58-0.61). The Youden index identified SOL = 18 minutes, WASO = 21 minutes, SE = 92%, and TST = 388 minutes as the sleep diary measures that yielded the highest sensitivity and specificity values for insomnia-control discrimination. Accounting for hypnotic medication and sleep apnea use did not change the findings.
Conclusion: Sleep diary parameters discriminated individuals with insomnia from good sleepers more accurately than actigraphy. These quantitative criteria are similar to those reported by other investigators using different methods and samples, including younger adults. The results suggest that the sleep diary, an inexpensive self-report sleep measure, may be used in clinical and research settings to help distinguish older adults with and without insomnia.