Vagus Nerve Stimulation Could Slow Ageing, Improve Mood and Sleep Quality
Highlights of Research
Scientific evidence now supports the benefits of vagus nerve stimulation (VNS) in reversing signs of ageing, improving mood, and enhancing sleep quality.
The newly published study by the University of Leeds could transform how we understand the ageing process and reshape the quality of life for many people.
The Wandering Nerve
The vagus nerve is also known as the "wandering nerve". It is the longest cranial nerve and has the widest distribution in the human body.
It passes through the ear and neck, into the thorax and the abdomen. Because of its extensive reach, the vagus nerve plays a crucial role in regulating functions of vital organs including the heart, brain, and lungs.
The Signs of Ageing
Primarily, the vagus nerve regulates the autonomic nervous system (ANS) - the integral nervous system that controls involuntary bodily functions.
The ANS has two branches: the sympathetic system that activates the "fight or flight" response and the parasympathetic system that oversees the "rest and digest" functions.
The sympathetic and parasympathetic system work in a complementary fashion to each other. When the body activates the sympathetic neural system, the parasympathetic tone will be reduced.
However, as we age, the balance between the two systems slowly tips towards the sympathetic end.
This decline is associated with many known health issues, including heart failures, hypertension, depression, and worsening sleep quality[3–5].
What are the New Discoveries?
The researchers investigated the effects of transcutaneous (non-invasive) vagus nerve stimulation (tVNS) in volunteers who were more than 55-year old - the population that was most vulnerable to age-related complications.
They found that a single tVNS treatment session could significantly increase heart rate variability (HRV) compared to control treatment. This shows the ability for tVNS to increase parasympathetic tone as measured by HRV, which is significant as low HRV has been associated with an increased risk of cardiovascular events[6,7].
Also, the use of tVNS for just 15 minutes daily over two weeks showed similar benefits to autonomic function in addition to improvements in depression score, sleep quality, and other aspects in the quality-of-life measurement.
More importantly, volunteers who had a greater sympathetic tone at the beginning of the study showed a better response over the two week period. This demonstrated that people who were at a higher risk would benefit most from tVNS.
The Gateway to the Nervous System
An added value of tVNS was the ability to influence the nervous system without any harm or pain to the volunteers compared to other alternative methods.
This was achieved via a small branch of the vagus nerve located at the outer ear.
These locations were the gateway that allowed pulses of stimulation to be transmitted through the skin to the nerve.
The method was effective and safe. The study reported that participants were comfortable during the stimulation procedure, where only a few experienced "tingling" sensations at the stimulation site.
Benefits to the Ageing Society
Healthy ageing is now a priority in our society. Instead of combating diseases after they have manifested, it is always a better choice to expand the period where healthy ageing can occur.
The capacity of tVNS to reduce the shift towards sympathetic prevalence and improve vagal tone is a promising discovery to reduce the impact of many chronic illnesses.
Studies have demonstrated that patients with coronary artery disease who received tVNS treatment had better exercise tolerance and required less medication.
Some other studies also described the beneficial effects of tVNS in reducing inflammation - the hallmark of ageing - and its associated problems.
Excessive inflammation was associated with many illnesses such as depression and chronic fatigue syndrome, all of which have shown to benefit from tVNS treatment.
Tip of the Iceberg
According to the lead author of the study, the findings “are just the tip of the iceberg”.
This study has opened doors to broader applications of tVNS and inspired research interest into something that touches us all.
Given the non-invasive, non-pharmacological nature of tVNS, it could emerge as the therapy of choice that is both safe and effective for a range of chronic diseases.
1 Tewfik T. Vagus Nerve Anatomy. Medscape. 2017.https://emedicine.medscape.com/article/1875813-overview#a1 (accessed 31 Aug 2019).
2 Bretherton B, Atkinson L, Murray A, et al. Effects of transcutaneous vagus nerve stimulation in individuals aged 55 years or above: potential benefits of daily stimulation. Aging (Albany NY) 2019;11:4836–57. doi:10.18632/aging.102074
3 Bibevski S, Dunlap ME. Evidence for impaired vagus nerve activity in heart failure. Heart Fail Rev 2011;16:129–35. doi:10.1007/s10741-010-9190-6
4 Gerritsen J, Dekker JM, TenVoorde BJ, et al. Impaired Autonomic Function Is Associated With Increased Mortality, Especially in Subjects With Diabetes, Hypertension, or a History of Cardiovascular Disease: The Hoorn Study. Diabetes Care 2001;24:1793–8. doi:10.2337/diacare.24.10.1793
5 Taylor CB. Depression, heart rate related variables and cardiovascular disease. Int J Psychophysiol 2010;78:80–8. doi:10.1016/j.ijpsycho.2010.04.006
6 Goldberger JJ, Challapalli S, Tung R, et al. Relationship of Heart Rate Variability to Parasympathetic Effect. Circulation 2001;103:1977–83. doi:10.1161/01.CIR.103.15.1977
7 Hillebrand S, Gast KB, de Mutsert R, et al. Heart rate variability and first cardiovascular event in populations without known cardiovascular disease: meta-analysis and dose–response meta-regression. EP Eur 2013;15:742–9. doi:10.1093/europace/eus341
8 Zamotrinsky A., Kondratiev B, de Jong J. Vagal neurostimulation in patients with coronary artery disease. Auton Neurosci 2001;88:109–16. doi:10.1016/S1566-0702(01)00227-2
9 BBC News. Ear ‘tickling’ therapy could ‘help thwart ageing’. BBC News. 2019.