Specific EEG Sleep Pattern in the Prefrontal Cortex in Primary Insomnia

Objective
To assess the specific prefrontal activity in comparison to those in the other main cortical areas in primary insomnia patients and in good sleepers.
Methods
Fourteen primary insomnia patients and 11 good sleepers were included in the analysis. Participants completed one night of polysomnography in the sleep lab. Power spectra were calculated during the NREM (Non-rapid eyes movements) and the REM (Rapid eyes movements) sleep periods at prefrontal, occipital, temporal and central electrode positions.
Results
During the NREM sleep, the power spectra did not differ between groups in the prefrontal cortex; while primary insomnia patients exhibited a higher beta power spectrum and a lower delta power spectrum compared to good sleepers in other areas. During the REM sleep, the beta1 power spectrum was lower in the prefrontal cortex in primary insomnia patients compared to good sleepers; while no significant difference between groups was obtained for the other areas.
Conclusions
The present study shows a specific prefrontal sleep pattern during the whole sleep period. In addition, we suggest that primary insomnia patients displayed a dysfunction in the reactivation of the limbic system during the REM sleep and we give additional arguments in favor of a sleep-protection mechanism displayed by primary insomnia patients.

研究目标：评估原发性失眠患者与优质睡眠者的前额叶皮层活动，并与其他主要皮层区域的活动进行对比分析。
研究方法：本分析共纳入14例原发性失眠患者与11例优质睡眠者。所有受试者于睡眠实验室完成1晚的多导睡眠监测（polysomnography）。分别在非快速眼动（NREM, Non-rapid eye movements）睡眠与快速眼动（REM, Rapid eye movements）睡眠期间，于前额叶、枕叶、颞叶及中央区电极位点计算功率谱。
研究结果：非快速眼动睡眠阶段，两组受试者前额叶皮层的功率谱无显著组间差异；而相较于优质睡眠者，原发性失眠患者在其余皮层区域的β功率谱更高、δ功率谱更低。快速眼动睡眠阶段，原发性失眠患者的前额叶皮层β1功率谱显著低于优质睡眠者，其余皮层区域则未观察到组间显著差异。
研究结论：本研究证实全睡眠周期内存在特异性的前额叶睡眠模式。此外，本研究提示原发性失眠患者在快速眼动睡眠阶段存在边缘系统再激活功能障碍，并为原发性失眠患者所具备的睡眠保护机制提供了额外的佐证依据。