“…The spectral analysis was performed on overnight EEG, significant higher beta power in CIs during W, N1, N2, NREM, and whole night, which were consistent with data from previous studies ( Merica, 1998 ; Perlis et al, 2001a ; Corsi-Cabrera et al, 2012 ; Spiegelhalder et al, 2012 ; Kang et al, 2018 , 2022 ; Smagula et al, 2021 ; Shi et al, 2022 ; Xu et al, 2022 ; Zhang et al, 2022 ). In a recent meta-analysis, elevated relative beta power in W, NREM and whole night was also be demonstrated by Zhao et al; however, they did not explore EEG spectral power in specific N1, N2 and N3 stages, which differ in function and depth of sleep ( Zhao et al, 2021 ).…”