Neuromodulation in sleep disorders.

Sleep disorders are a growing global health issue with profound consequences on cardiovascular health, metabolic functioning, cognitive output and overall quality of life. Although there have been numerous clinical advances in brain-based treatments for sleep disorders, there are still a number of sleep disorders that are not well understood and need new treatment options to address the underlying neural mechanisms of sleep-wake regulation. Recent advances in neuroscience have highlighted neuromodulation as a promising treatment option for the complex neural mechanisms of sleep-wake dysfunction. This chapter provides an overview on the neurobiological basics of neuromodulation in sleep medicine, including neurobiological circuits, circadian processes of sleep, wakefulness and their disorders in brain and potential targeting biomarkers for brain stimulation. Present non-invasive neuromodulation strategies include transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), vagus nerve stimulation, etc.; new and invasive neuromodulation strategies such as deep brain stimulation (DBS) for insomnia, obstructive sleep apnea (OSA) and periodic leg movement disorder (PLMD). In this paper, we review the current level of evidence and provide an overview on the road ahead to bring brain stimulation to the daily practice of sleep medicine.