Sleep EEG power spectra, insomnia, and chronic use of benzodiazepines

Study Objectives: The present study examined the sleep microstructure in relation to insomnia and chronic use of benzodiazepines in older adults. Participants: The participants were 46 older adults, aged 55 or older (mean age = 62.9), who were divided into three groups: insomnia sufferers using BZ chronically (n = 15), drug-free insomnia sufferers (n = 15), and self-defined good sleepers (n = 16). Design: Participants completed 3 consecutive nights of polysomnography in the laboratory. Spectral analyses were carried on the second night of sleep recordings. Stages 2, 3, and 4 of the first 4 cycles of the second night were retained for the analysis. Results: Results showed no significant differences between drug-free insomnia sufferers and good sleepers. However, benzodiazepine users exhibited significantly less delta and theta activity over the night than did good sleepers. When compared to drug-free insomnia sufferers, benzodiazepine users had less delta and theta activity within cycle 2 only. Regarding high-frequency bands, benzodiazepine users had more beta 1 activity within cycle 3 than did good sleepers and more than both drug-free insomnia sufferers and good sleepers within cycle 4. Conclusions: The findings show that spectral analysis is an efficient tool to detect and quantify the effects of benzodiazepine use on sleep structure, particularly with older adults, a group for whom macrostructure sleep alterations due to physiologic aging are hard to distinguish from sleep changes induced by insomnia and the use of hypnotic drugs. In addition, these results raise important questions about the effects and indications of prolonged use of benzodiazepine medications in older adults with insomnia complaints.