Longitudinal course of insomnia: Age-related differences in subjective sleepiness and vigilance performance in a population-based sample

Objective: The present study utilized a population-based sample investigating the following aims: (1) compare the longitudinal course of insomnia in middle-aged and older adults and (2) examine age-related differences on subjective complaint and objective performance in middle-aged and older adults based on the course of insomnia. Methods: 1657 middle-aged adults (48.16% male, mean age. = 55.35. ±. 4.03. years) and 405 older adults (48.40% male, mean age. = 70.13. ±. 3.88. years) from the Korean Genome and Epidemiology Study (KoGES) were classified into 4 groups - no insomnia (NI), single episode insomnia (SEI), remitted persistent insomnia (PI-R), and ongoing persistent insomnia (PI-O) based on their course of insomnia over 5 time points spaced two years apart. Their performance on the psychomotor vigilance task (PVT) and subjective daytime sleepiness were compared across different insomnia groups, and the results were compared between middle-aged adults and older adults. Results: Analysis of covariance indicated that subjective daytime sleepiness was significantly different across the insomnia groups in middle-aged adults based on insomnia group (P. = <. .0001), but, did not affect objective vigilance performance. In contrast, older adults displayed significantly different PVT response time, but not daytime sleepiness, based on insomnia group (P. = 0.03). Conclusion: Insomnia impacts psychomotor performance and subjective sleepiness differently, based on age group. There may be underlying processes associated with the aging that amplifies the impact of insomnia on vigilance performance, yet lessens perceived sleepiness in older adults.