Insomnia Disorder patients showed higher occipital IAF power during the period before sleep onset compared to healthy controls, with faster IAF associated with longer sleep latency and higher IAF power related to greater insomnia severity and stronger sleep state misperception.
Key Findings
Results
Insomnia Disorder patients showed higher occipital Individual Alpha Frequency (IAF) power during the Before-Sleep Onset period compared to Healthy Controls.
Analysis focused on occipital regions during the period preceding sleep onset (Before-SO)
Group differences were found specifically in IAF power, not in broadband alpha activity
No group differences emerged in broadband alpha activity between ID patients and HCs
Polysomnographic recordings were used to assess changes in alpha activity and IAF
Results
Faster IAF was associated with longer sleep latency and delayed transition to deep sleep.
Correlational analyses were conducted to investigate associations between alpha activity, IAF, sleep parameters, and sleep state misperception
Faster IAF (higher individual alpha frequency in Hz) specifically predicted impaired sleep initiation
The association extended to delayed transition to deep sleep stages, not only sleep onset latency
These associations were identified in occipital regions during the Before-SO period
Results
Higher IAF power was associated with greater insomnia severity and stronger Sleep State Misperception (SSM).
Correlational analyses linked IAF power to both subjective insomnia severity and SSM
SSM refers to discrepancy between objectively measured and subjectively perceived sleep
IAF power and IAF (frequency) showed dissociable associations with different sleep-related outcomes
These findings suggest IAF power captures both the clinical burden of insomnia and perceptual distortions of sleep
Discussion
IAF during the pre-sleep onset period is proposed as a sensitive marker of cortical arousal contributing to impaired sleep initiation and distorted sleep perception.
The study hypothesized that IAF as an individualized marker would better capture sleep-initiation alterations than broadband alpha power
Results supported IAF over broadband alpha as a more sensitive electrophysiological marker
IAF is described as contributing to both impaired sleep initiation and distorted sleep perception in ID
Authors frame cortical arousal as the mechanistic link between elevated IAF and insomnia features
Conclusions
IAF is proposed as a potential electrophysiological marker of Insomnia Disorder pathophysiology and a target for personalized therapeutic interventions.
The study frames IAF as relevant for 'personalized neurophysiological characterization of insomnia' as stated in the title
Authors suggest IAF could serve as a target for personalized therapeutic interventions
The individualized nature of IAF (as opposed to fixed broadband frequency ranges) is highlighted as a methodological advantage
Findings are described as underscoring 'the potential role of the IAF as an electrophysiological marker of ID pathophysiology'
What This Means
This research suggests that examining brain wave activity in a very specific and personalized way — measuring each person's own individual peak alpha frequency (IAF) rather than using a one-size-fits-all frequency range — may reveal important brain differences in people with insomnia that standard methods miss. The study recorded brain activity using sleep studies (polysomnography) in people with insomnia and healthy sleepers, focusing on the period just before falling asleep. While no differences were found between the two groups when looking at broad alpha wave activity (the conventional approach), clear differences emerged when looking at IAF specifically: people with insomnia had higher IAF power in the back of the brain just before sleep onset.
The findings also showed that the speed and strength of these personalized alpha brain signals were linked to specific sleep problems in meaningful ways. People with faster IAF took longer to fall asleep and took longer to reach deep sleep, while people with stronger IAF power reported worse insomnia symptoms and were more likely to misjudge how much sleep they actually got — a phenomenon known as sleep state misperception, where people feel like they slept poorly even when objective recordings show otherwise.
This research suggests that measuring IAF could be a more sensitive tool for understanding what goes wrong in the brains of people with insomnia, particularly in terms of difficulty 'switching off' the brain at bedtime. Because IAF is unique to each individual, it may also open doors to more personalized treatments — such as brain stimulation techniques tuned to a person's own brain frequency — rather than applying the same approach to everyone with insomnia.
Fasiello E, Gorgoni M, Berra F, Salabelle R, Casoni F, Proserpio P, et al.. (2026). Individual alpha frequency before the sleep onset: towards a personalized neurophysiological characterization of insomnia.. Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. https://doi.org/10.1016/j.clinph.2026.2111720