Objective:

Assessment of EEG power spectra in patients with Insomnia Disorder (ID): A meta-analysis.

Background:

EEG is an essential tool in diagnosing sleep disorders, including insomnia and stress-related disorders. Insomnia disorder (ID) is identified by persistent difficulty initiating and maintaining sleep, affecting approximately 10% of the population. Alterations in EEG power spectra, such as increased high-frequency activity in the beta and/or gamma range and decreased activity in other frequency bands, have been observed in ID, potentially reflecting cortical hyperarousal.

Design/Methods:

We conducted a meta-analysis of 18 studies involving 577 participants to examine EEG power spectra across six frequency bands (alpha, theta, gamma, delta, beta, sigma) during wakefulness and different sleep stages (NREM and REM). Data was sourced from databases, including PubMed and ScienceDirect. EEG recordings were analyzed using Empirical Mode Decomposition (EMD).

Results:

Insomnia Disorder (ID) patients exhibited increased beta and gamma power during wakefulness and sleep, indicating cortical hyperarousal. During NREM sleep, significant increases in beta power and a decrease in delta power were observed. REM sleep also showed increased alpha, sigma, and beta power. Benzodiazepine use was associated with increased sigma and decreased delta and theta activity during sleep but increased theta during wakefulness. Some studies had limitations, including inconsistent frequency band subdivisions and limited data on REM sleep.

Conclusions:

Our findings underscore the need for further research in this area, particularly in enhancing spectral analysis methods, examining differences among insomnia subtypes, and adhering to standard guidelines for frequency band reporting.