Hybrid neuromodulation for treatment-resistant insomnia: combining acupuncture with electrical/brain stimulation, with particular relevance to hyperarousal phenotypes

Refractory insomnia, defined here as chronic insomnia disorder persisting for at least 3 months and ≥3 nights per week despite adequate evidence-based behavioral therapy and at least one pharmacologic trial, remains difficult to treat and is likely driven by large-scale network dysfunction and thalamocortical dysrhythmia. Standard monotherapies, including pharmacotherapy, cognitive-behavioral therapy for insomnia, acupuncture, or standalone non-invasive brain stimulation, often provide incomplete or transient benefit. This narrative review proposes a targeted hybrid neuromodulation strategy for refractory insomnia, particularly hyperarousal phenotypes, combining peripheral somatic acupuncture with central non-invasive brain stimulation such as tDCS, tACS, or rTMS. We introduce the NECTAR (NEurochemical, Cortical, and autonomic Tandem Augmentation of Rest) framework, a hypothesis-generating model suggesting that acupuncture may prime autonomic, neurochemical, and network states to enhance the efficacy and durability of subsequent cortical stimulation. Preliminary preclinical and clinical findings suggest potential safety and synergistic effects, but mechanistic links remain unproven. Rigorous trials with multimodal biomarkers, optimized sequencing, and individualized protocols are needed. Accordingly, NECTAR should be viewed as an exploratory framework for refractory insomnia rather than an established clinical recommendation.