Received Date: August 09, 2016; Accepted Date: January 30, 2017; Published Date: February 13, 2017
Citation: Yu Y, Guo X, Chen G, Li S, Rong P (2017) Transcutaneous Auricular Vague Nerve Stimulation: A Promising Alternative Therapy for Insomnia Disorder. Brain Disord Ther 6:227. doi: 10.4172/2168-975X.1000227
Copyright: © 2017 Yu Y, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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Insomnia disorder is causing great economic burden to the society. Conventional pharmacotherapies are with multiple adverse effects to people. Auricular acupuncture (AA) inspired us to invent transcutaneous auricular vagus nerve stimulation (taVNS) years ago. We accidently found that taVNS could improve patients sleeping conditions in depressed and in epilepsy patients. And, taVNS is with little side effect. We considered that taVNS is a promising alternative therapy for insomnia disorder with a bright future.
AA: Auricular Acupuncture; taVNS: Transcutaneous Auricular Vagus Nerve Stimulation; ID: Insomnia Disorder; CAM: Complementary and Alternative Medicine
Insomnia disorder (ID) is a common condition that includes difficulty in initiating sleep, maintaining sleep, waking up too early, and nonrestorative or poor-quality sleep, all of which are commonly associated with symptoms of daytime functional impairment . According to a WHO collaborative study in 14 countries, 16% of correspondents had difficulty falling asleep; 25% of the correspondents either experienced difficulty staying asleep or woke up too early . The prevalence is even higher in the elderly and twice as high in women as in men [3,4]. Daytime complaints of people with insomnia concern cognitive functioning , fatigue , and depressed mood . Moreover, insomnia leads to higher risks of depression , anxiety  and cardiovascular diseases . Daytime consequences and functional impairment caused a heavy economic burden to the society . It was estimated that the total annual cost of insomnia in 1994 was approximately $30-$35 billion in the USA . Now-a-days, the number should be much higher.
Conventional approaches to the treatment of chronic insomnia usually involve either pharmacotherapies or psychological interventions. Pharmaceutical hypnotics are the primary first-line pharmacotherapy used to treat chronic insomnia . The use of benzodiazepines such as diazepam and related drugs, or non-benzodiazepine hypnotics e.g. zolpidem or zopiclone are preferred currently over older barbiturates which can cause death in cases of overdose . With respect to benzodiazepines, although a relatively safe class of medication, concerns exist over dependency, and currently most guidelines endorse only short-term use for insomnia. Sedating antipsychotics, such as olanzapine or quetiapine, and sedating antidepressants, including the older tricyclic drugs, are also commonly prescribed ‘off label’ for chronic insomnia, particularly in later life . The use of these drugs has the potential to cause serious side effects .
Complementary and alternative medicine (CAM) now-a-days is prevalent by sufferers of psychiatric disorders, commonly for the management of depression, anxiety, or insomnia [15-17]. Most CAM therapies are with little side effects, which attract more and more people to use them. Approximately 60% reported use of CAM to their conventional medical practitioner. Younger, more educated persons were more likely to use CAM to treat their insomnia .
Acupuncture is an important part of CAM. Auricular acupuncture (AA) (Figure 1) is an important branch of acupuncture . It is a therapeutic method by which specific points on the auricle are stimulated to treat various conditions. AA is often recommended as treatment for insomnia . AA inspired us to invent transcutaneous auricular vagus nerve stimulation (taVNS) years ago. Vagus nerve stimulation (VNS) has been approved by FDA (Figure 2) for epilepsy in 1997  and treatment-resistant depression in 2005 [22,23]. However, some factors limited VNS to patients, including high cost, the involvement of surgery, perioperative risks, and potentially significant side effects . Based on anatomical studies which suggest that the ear is the only place on the surface of human bodies where there is afferent vagus nerve distribution [25,26], especially in the auricular concha  (Figure 3), a direct current stimulation of these afferent nerve fibers superficially on ear supposes to has similar effect to classic VNS without surgical intervention . In order to overcome the disadvantages of classic VNS, we developed taVNS. And we accidently found that taVNS could improve patients sleeping conditions in depressed patients  and in epilepsy patients  during our clinical studies process. In addition, taVNS can trigger melatonin secretion, which may be one of the key mechanisms of improving sleeping conditions in patients .
A systematic review and meta-analysis revealed a positive effect of AA for primary insomnia . Another feasibility study found that an AA insomnia regimen may improve sleep quality and daytime dysfunction among veterans with post-traumatic stress disorder . Auricular points acupressure also helps increase the sleep duration and decrease wake after sleep onset .
However, few studies are using taVNS on insomnia disorder. So, we are collecting participants with insomnia disorder to proceed a multicenter, randomized, double-blind controlled prospective study . Because of the continuous current stimulation, we considered that taVNS should have a better efficacy than AA. The result is worth looking forward to it.
Overall, between 6% and 10% of adults meet the diagnostic criteria for insomnia disorder . That will be approaching or exceeding 1 billion people globally, which causing great economic burden to the society. Conventional pharmacotherapies are with multiple adverse effects, which arouse the use of CAM therapies. Auricular acupuncture (AA), which is often recommended as treatment for insomnia , inspired us to invent transcutaneous auricular vagus nerve stimulation (taVNS) years ago (Figure 4). We accidently found that taVNS could improve patients sleeping conditions in depressed patients  and in epilepsy patients  during our clinical studies process. We considered that taVNS is a promising alternative therapy for insomnia disorder with a bright future.