Infra-slow EEG neurofeedback for insomnia: a single-case experimental study in primary care

Insomnia is a prevalent and burdensome condition in primary care, associated with impaired functioning, increased health risks, and suffering. Infra-slow neurofeedback (ISF-NF) has been proposed as an intervention for stress-related sleep dysregulation, yet empirical evidence from primary care remains scarce.

To examine the feasibility, acceptability, and preliminary effects of ISF-NF for insomnia in primary care using a single-case experimental design.

A single-case experimental design with repeated measures was applied. Ten patients with insomnia and related comorbidities (e.g., stress-related exhaustion, migraine, anxiety) were enrolled. Nine completed the intervention, and eight had sufficient data for analysis following a 2-week baseline and 12 weekly ISF-NF sessions with individualized adjustment of the temporal integration (frequency) parameter. Subjective sleep quality was assessed daily using the Brief Self-Reported Sleep Quality Assessment (BSRSQA). Standardized questionnaires including the Pittsburgh Sleep Quality Index (PSQI), Patient Health Questionnaire-9 (PHQ-9), and Generalized Anxiety Disorder-7 (GAD-7) were collected at baseline, post-intervention, and 3-month follow-up. Treatment effects were evaluated using visual analysis and non-parametric Tau-U statistics. Wearable sleep data (Fitbit Inspire 3) were analyzed descriptively to contextualize subjective outcomes.

Visual single-case analyses revealed heterogeneous but interpretable trajectories, with several participants showing improved perceived sleep quality. Five of eight participants demonstrated statistically significant Tau-U effects (p < 0.05). Group-level analyses showed reductions in sleep problems (PSQI) and depressive symptoms (PHQ-9) from pre to post-intervention, with partial return toward baseline at three-month follow-up. Wearable sleep metrics indicated variability and limited convergence with total sleep time but suggested improvements in sleep consolidation and timing in some cases. Feasibility and acceptability were supported by high treatment adherence, therapeutic alliance, and few reported adverse effects.

These findings suggest that ISF-NF may be a feasible and well-tolerated intervention in a primary care context, with preliminary indications of benefit in a subset of individuals. Effects were heterogeneous and should be interpreted cautiously. Individualized parameter adjustment and visual single-case analysis may provide a useful framework for capturing treatment dynamics in adaptive interventions. Wearable sleep data may offer contextual information but should be interpreted alongside subjective outcomes. Controlled studies are needed to evaluate efficacy and underlying mechanisms.