Botulinum toxin therapy for neurological disorders: Serendipitous benefits on sleep quality and underlying mechanisms.

Botulinum toxin (BoNT) remains the gold standard treatment for focal and segmental dystonia and is widely used in managing hyperkinetic disorders, chronic pain, and glandular hypersecretion. Extensive clinical trials demonstrate that BoNT effectively ameliorates both the core symptoms of these neurological conditions and their frequently associated comorbidities, including depression, anxiety, and diminished quality of life. Notably, many BoNT-treated neurological disorders co-occur with sleep disturbances, yet sleep outcomes remain underexplored. This review synthesizes current evidence on sleep outcomes following BoNT treatment of both established neurological indications (e.g., neuropathic pain, chronic migraine, dystonia, spasticity, sialorrhea, hemifacial spasm, bladder dysfunction) and primary sleep disorders (e.g., restless legs syndrome, sleep bruxism, insomnia). As a result, BoNT treatment improves sleep outcomes across both categories, potentially through mechanisms involving modulation of vasomotor tone, hormonal secretion, neural activity, mood, and pain perception. However, larger, rigorously designed randomized controlled trials are essential to definitively confirm these therapeutic effects and elucidate the underlying neurobiological mechanisms.