Research
Mixed
In subjective insomnia patients, diminished low-frequency (delta) and elevated high-frequency (alpha, sigma, beta) NREM EEG activity is associated with greater subjective sleep complaints and greater underestimation of sleep time.
For those who feel they get no sleep despite a normal sleep study, the problem is likely 'hyperarousal' (high brain activity) rather than 'sleep loss'. This suggests treatments targeting relaxation and reducing cortical arousal (like CBT-I) may be more effective than those simply trying to extend sleep time.
GoodSupportsHIGH confidence
For the subjective insomnia subjects, diminished low-frequency and elevated higher frequency non-REM EEG activity was associated with their sleep complaints.
Why this rating
Robust regression analysis controlling for age, sex, and mood symptoms (BDI, STAI) confirms the association.
Source
NREM Sleep EEG Frequency Spectral Correlates of Sleep Complaints in Primary Insomnia Subtypes
Andrew D. Krystal et al. · SLEEP · 2002
DOI 10.1093/sleep/25.6.626
cross_sectional · n=50Cited 352×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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