Research

Mixed

In patients with subjective primary insomnia (normal PSG but high sleep complaint), NREM sleep exhibits significantly lower delta power and higher alpha, sigma, and beta power compared to normal controls, reflecting heightened cortical arousal.

If you have insomnia but your sleep study shows you are getting enough sleep, your issue may be '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.

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Lower delta and greater alpha, sigma, and beta NREM EEG activity were found in the patients with subjective insomnia but not those with objective insomnia, compared with the normal subjects.
Andrew D. Krystal et al. · SLEEP · 2002

Why this rating

Randomized controlled observational study with clear subtyping criteria, robust statistical analysis (MANCOVA), and replication of previous findings in a specific subgroup.

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×
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DOI resolved against Crossref · corpus check 2026-06-10

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