ZenoWell vagus nerve stimulation for women’s wellness

Why hormonal shifts affect sleep, mood, stress, and pain

During the menstrual cycle, estrogen and progesterone rise and fall across different phases. These hormones do far more than act on the uterus and ovaries—they also affect the brain, blood vessels, and neural circuits that control heart rate, blood pressure, mood, and pain perception.

A 2025 review in NeuroSci looked specifically at how the menstrual cycle influences the autonomic nervous system. The authors examined indicators like heart rate variability (HRV, a marker of vagal activity), baroreflex sensitivity (how well the body stabilizes blood pressure), and sympathetic nerve activity. The patterns they found match what many women feel in real life: certain phases are associated with more fatigue, irritability, poor sleep, and increased sensitivity to pain.

In simple terms:

Around menstruation, when both estrogen and progesterone are low, the body tends to drift into a “stress‑like” mode. The sympathetic system becomes more active, the vagus nerve is relatively less engaged, heart rate may be slightly higher, and the body feels more tense. Many women experience lower mood, more anxiety, and greater sensitivity to pain in this phase. This is why you may feel more “fragile” or on edge around your period—it’s not you overreacting; your nervous system is literally in a different physiological state.

Around ovulation, when estrogen rises, some studies suggest vagal activity improves and many women feel more emotionally stable, more energetic, and clearer in their thinking. In the luteal (pre‑menstrual) phase, progesterone rises again and is linked in some research to increased sympathetic drive and reduced vagal regulation. For some women, this shift contributes to PMS or PMDD: irritability, depressed mood, anxiety, insomnia, or feeling easily overwhelmed, often have an autonomic component behind them.

Menopause tells a similar story, but stretched over years instead of days. A 2025 review in Autonomic Neuroscience highlighted that cardiovascular risk in women rises sharply around menopause, and a major reason is the loss of estrogen’s protective influence on the autonomic and vascular systems. With age, sympathetic activity naturally increases, but in women around midlife this rise can be steeper. When estrogen levels fall:

• Sympathetic “gas pedal” activity tends to increase
• Vagal “brake” on heart rate and blood pressure becomes weaker
• Blood vessels become stiffer and less responsive

Common menopausal symptoms like hot flashes, night sweats, poor sleep, palpitations, and mood swings are all closely tied to these autonomic shifts.

You can think of it this way: whether it’s the monthly menstrual cycle or the menopausal transition, hormones are constantly turning the dials on the autonomic nervous system. When the sympathetic system stays “on” too much and the vagus nerve is underactive, women are more likely to feel anxious, in pain, exhausted, sleepless, and physically unsteady.

The vagus nerve: the master regulator of body–mind balance

The vagus nerve is the main parasympathetic nerve in the body. It runs from the brainstem down to the heart, lungs, and digestive organs. It’s like a high‑speed communication highway: it sends information from the organs to the brain and carries “rest, heal, and calm down” messages from the brain back to the body.

For women, the vagus nerve is deeply involved in several key areas:

First, stress and cortisol regulation. The better your vagal tone, the more resilient you tend to be under stress. You can recover more quickly after something stressful happens. When vagal tone is low, it’s easy to feel stuck in a “constant fight‑or‑flight mode”: always tense, easily overwhelmed, and unable to fully relax.

Second, pain and inflammation. The vagus nerve helps control inflammatory responses through what’s called the cholinergic anti‑inflammatory pathway. Inflammation, pain, and mood are often tightly connected. Many people with chronic pain also struggle with anxiety and depression. Research suggests that supporting vagus nerve activity can help improve pain and emotional distress in certain conditions.

Third, heart rate and blood pressure. The vagus nerve is the body’s natural brake: it slows the heart rate and helps keep blood pressure variability within a healthy range. This is especially important around menopause, when sympathetic activity tends to rise; without enough vagal braking, palpitations and high blood pressure can become more common.

Finally, mood and cognition. Vagal signals influence brain areas involved in emotional regulation, attention, and decision‑making. Better vagal function is often associated with stronger self‑regulation and emotional stability.

So when women experience mood swings, worsening pain, poor sleep, or heightened stress around “that time of the month,” postpartum, or during peri‑ and post‑menopause, what’s happening under the surface is often a shift toward sympathetic dominance and reduced vagal regulation—the autonomic system is out of balance.

What is taVNS, and how might it help?

Transcutaneous auricular vagus nerve stimulation (taVNS) sounds technical, but the principle is quite straightforward. Certain parts of the outer ear—such as the cymba concha and cavum concha—are innervated by a branch of the vagus nerve. By placing small electrodes on these spots and delivering very mild, safe electrical pulses, we can gently activate the vagus nerve through the skin.

Unlike traditional implanted VNS, taVNS:

• Requires no surgery
• Is applied externally on the ear
• Can be used at home or in daily life
• Is non‑invasive and designed to be comfortable

You can think of it as a “gentle nerve therapy through the ear” that you can integrate into your routine.

In women’s health, the clearest and most direct evidence so far comes from studies on primary dysmenorrhea (menstrual pain without structural disease like fibroids or endometriosis).

A randomized controlled trial published in Neuromodulation in 2025 recruited 34 women with primary dysmenorrhea. They were randomly assigned to either real taVNS or sham stimulation (which looked the same but did not actually stimulate the vagus nerve). The treatment protocol was simple: starting 5 days before the expected second menstrual period, the women used taVNS once a day for 5 consecutive days. Electrodes were placed on the tragus and nearby ear areas, with stimulation at 10 Hz for 5 minutes at a comfortable intensity.

The results were striking. Compared with the sham group, women using taVNS had significantly less pain during their next period. Their pain ratings went down, and their tolerance to pressure pain improved. Importantly, it wasn’t just the pain that changed: their menstrual symptom questionnaires showed fewer daily life disruptions, their anxiety scores dropped, and they even did better on a 6‑minute walking test, reflecting better physical functioning and overall state. This suggests that taVNS is not simply “numbing the pain,” but helping the nervous system regulate pain and emotional responses more effectively.

An earlier pilot study in Brain Stimulation also found that 10 days of taVNS applied to the left ear reduced both the duration and intensity of menstrual pain, along with overall menstrual symptom burden.

Taken together, these studies point in the same direction: gentle vagus nerve stimulation through the ear can reduce menstrual pain, lower pain sensitivity, and ease the anxiety and emotional toll that often come with painful periods.

Although the uploaded articles focus mainly on dysmenorrhea and the autonomic aspects of menopause, other research has explored taVNS in migraine, depression, certain abdominal pain conditions, and sleep problems, with encouraging results. For women in midlife and beyond, there is a strong theoretical basis for using taVNS to support:

• Distress related to hot flashes and night sweats
• Menopause‑related anxiety, stress, and autonomic “over‑activation”
• Heart rate and blood pressure regulation as an adjunct to medical care

In other words, taVNS is not a magic cure for one specific disease, but a way to support vagus nerve function and autonomic balance—helping the body maintain inner stability across changing hormonal landscapes.

Our vision: a “pocket‑sized comfort tool” for hormonal transitions

We hope taVNS can become more than just a neuromodulation device. Our vision is for it to be a supportive tool women can lean on across different life stages.

For many, “those days” mean pain, low mood, reduced productivity, and a tendency to withdraw from social life. The premenstrual days can bring irritability and anxiety. Perimenopause can feel like a long rollercoaster of emotional and physical upheaval. Our wish is that you don’t have to simply endure all of this without support.

Imagine using taVNS as a small ritual of self‑care: in the days before your period, you take a few minutes for a session to gently prepare your nervous system. During painful days, you combine it with a hot water bottle, rest, and some deep breathing to help your body step back from constant sympathetic overdrive. On nights when premenstrual mood swings or anxiety keep you awake, a short taVNS session before bed, perhaps paired with meditation or calming music, becomes your way of pressing “pause”.

For women in menopause, taVNS could be a “pocket‑sized comfort tool” when hot flashes, night sweats, palpitations, or irritability flare up. Instead of feeling completely at the mercy of these symptoms, you have something practical to help you gradually regain a sense of control.

We also believe that beauty is not just about skin or appearance; it’s an inner sense of stability, safety, and vitality. When stress is lower, sleep is better, and pain no longer dominates your life, your entire presence changes. You don’t just look better—you genuinely feel better.

Our intention in developing taVNS technology is simple:

• To be there when you need support—not only in hospitals, but in your everyday life.
• To fit into the small pockets of time in your busy schedule and give you a moment of repair.
• To quietly accompany you through each hormonal wave, helping you move more smoothly through every cycle and every big transition.

Of course, research on taVNS in different aspects of women’s health—especially around menopause—is still evolving. Safety and proper use are extremely important. taVNS does not replace medical diagnosis or treatment. Women with heart disease, implanted pacemakers, epilepsy, pregnancy, or other special conditions should consult a healthcare professional before use. But as scientific evidence grows, we are already seeing that gently supporting the vagus nerve can genuinely help many women navigate those “hormone‑heavy” times with more ease.

Our vision is straightforward:
As your body and life change, we want you to be able to meet each phase more calmly, live more comfortably, and truly—feel better, look better, and glow always.

Reference: 

Kızkın, Zeynep Yıldız, Rıdvan Yıldız, and Ali Veysel Özden. "Effects of Transcutaneous Auricular Vagus Nerve Stimulation in Individuals with Primary Dysmenorrhea: A Randomized Controlled Trial." Neuromodulation: Technology at the Neural Interface (2025).

Lee, E. J., and M. L. Keller-Ross. "Menopause and its effects on autonomic regulation of blood pressure: Insights and perspectives." Autonomic Neuroscience (2025): 103295.

Roy, Sankanika, Elettra Agordati, and Thomas DW Wilcockson. "Autonomic nervous system, cognition, and emotional valence during different phases of the menstrual cycle—a narrative review." NeuroSci 6.3 (2025): 78.

Stokes, William H., et al. "Vasomotor symptoms of menopause, sympathetic activity, and blood pressure in postmenopausal females." American Journal of Physiology-Heart and Circulatory Physiology (2025).

Wang, Chenxi, et al. "Transcutaneous auricular vagus nerve stimulation for the treatment of primary dysmenorrhea: A pilot study." Brain Stimulation: Basic, Translational, and Clinical Research in Neuromodulation 16.3 (2023): 695-697.