Age-related changes in slow wave activity rise time and NREM sleep EEG with and without zolpidem in healthy young and older adults

Objective: Whether there are age-related changes in slow wave activity (SWA) rise time, a marker of homeostatic sleep drive, is unknown. Additionally, although sleep medication use is highest among older adults, the quantitative electroencephalographic (EEG) profile of the most commonly prescribed sleep medication, zolpidem, in older adults is also unknown. We therefore quantified age-related and regional brain differences in sleep EEG with and without zolpidem. Methods: Thirteen healthy young adults aged 21.9 +/- 2.2 years and 12 healthy older adults aged 67.4 +/- 4.2 years participated in a randomized, double-blind, within-subject study that compared placebo to 5 mg zolpidem. Results: Older adults showed a smaller rise in SWA and zolpidem increased age-related differences in SWA rise time such that age differences were observed earlier after latency to persistent sleep. Age-related differences in EEG power differed by brain region. Older, but not young, adults showed zolpidem-dependent reductions in theta and alpha frequencies. Zolpidem decreased stage 1 in older adults and did not alter other age-related sleep architecture parameters. Conclusions: SWA findings provide additional support for reduced homeostatic sleep drive or reduced ability to respond to sleep drive with age. Consequences of reduced power in theta and alpha frequencies in older adults remain to be elucidated. (C) 2014 Elsevier B.V. All rights reserved.