What We Know About Dysautonomia in Hypermobile EDS and Hypermobility Spectrum Disorders

Many people think of hypermobility as simply being "double-jointed."

Perhaps you've always been more flexible than your peers. Maybe you could do the splits as a child, bend your fingers in unusual ways, or were told you were simply "very flexible." For some individuals, hypermobility is relatively benign. For others, it may be part of a broader condition such as Hypermobile Ehlers-Danlos Syndrome (hEDS) or Hypermobility Spectrum Disorder (HSD).

What surprises many patients is that the symptoms often extend far beyond the joints.

Dizziness. Fatigue. Brain fog. Digestive problems. Bladder dysfunction. Temperature intolerance. Heart palpitations. Exercise intolerance. Anxiety-like symptoms.

At first glance, these symptoms may seem unrelated. Patients often find themselves seeing multiple specialists, collecting multiple diagnoses, and wondering whether anyone is looking at the bigger picture.

Increasingly, researchers believe that autonomic dysfunction—also known as dysautonomia—may be one of the important threads connecting many of these seemingly unrelated symptoms.

What Is the Autonomic Nervous System?

The autonomic nervous system (ANS) is the body's automatic control system. It regulates countless functions that occur without conscious thought, including:

• Heart rate
• Blood pressure
• Blood vessel tone
• Digestion and gut motility
• Bladder function
• Sweating
• Temperature regulation
• Breathing patterns

When functioning normally, the autonomic nervous system continuously adapts to keep the body in balance.

When it becomes dysregulated, symptoms can emerge throughout multiple organ systems.

Why Is Dysautonomia So Common in Hypermobile Patients?

Researchers do not yet have all the answers, but several overlapping mechanisms have emerged that may help explain the connection.

1. Connective Tissue Laxity and Blood Pooling

Connective tissue provides structural support throughout the body, including within blood vessel walls.

In individuals with hEDS and HSD, blood vessels may be more elastic and less able to maintain their shape against gravity. When standing, blood can pool excessively in the legs and lower body.

This reduces blood return to the heart and brain.

To compensate, the autonomic nervous system may increase heart rate and release stress hormones such as adrenaline in an attempt to maintain blood pressure and circulation.

For some individuals, this contributes to symptoms associated with Postural Orthostatic Tachycardia Syndrome (POTS), including:

• Dizziness
• Lightheadedness
• Rapid heart rate
• Brain fog
• Fatigue
• Exercise intolerance

2. Small Fiber Neuropathy

One of the most exciting areas of current research involves small fiber neuropathy (SFN).

Small nerve fibers help regulate many autonomic functions, including heart rate, blood pressure, digestion, sweating, temperature regulation, and bladder function. These nerves also play a role in pain and sensory perception.

Multiple studies have identified evidence of small fiber abnormalities in patients with hypermobile EDS and Hypermobility Spectrum Disorders. This suggests that autonomic symptoms may not simply be a secondary consequence of hypermobility but may also involve direct dysfunction of the nerves responsible for autonomic regulation.

In other words, the body's communication network itself may be impaired.

3. Dysfunction of the Body's Pressure Sensors

The body relies on specialized sensors called baroreceptors to detect changes in blood pressure and help regulate circulation.

Some researchers have proposed that connective tissue laxity may affect these pressure-sensing systems. If these sensors become overly sensitive—or less accurate—the nervous system may overreact to relatively minor changes in position or blood pressure.

This remains an area of ongoing investigation, but it may help explain why some patients experience dramatic symptoms when standing, during heat exposure, after meals, or when dehydrated.

4. Mast Cell Activation and Blood Vessel Instability

Many patients with hEDS and HSD also report symptoms consistent with Mast Cell Activation Syndrome (MCAS).

Mast cells release chemical mediators such as histamine that influence blood vessel tone, permeability, immune signaling, and inflammation.

When these mediators are released excessively, blood vessels may dilate, blood pressure may fluctuate, and symptoms such as flushing, palpitations, dizziness, itching, digestive symptoms, and fatigue may worsen.

While researchers are still working to fully understand the relationship between hypermobility, mast cells, and dysautonomia, clinicians frequently observe significant overlap among these conditions.

5. Deconditioning: Cause, Consequence, or Both?

Many individuals living with chronic pain, fatigue, dizziness, and exercise intolerance naturally become less active over time.

This can lead to cardiovascular deconditioning, including reduced blood volume and decreased cardiovascular fitness.

Unfortunately, deconditioning can worsen autonomic symptoms, creating a frustrating cycle:

Symptoms → Reduced Activity → Deconditioning → More Symptoms

Importantly, this does not mean dysautonomia is caused by being "out of shape." Rather, deconditioning often develops as a consequence of living with chronic symptoms and may further amplify the underlying problem.

Why So Many Patients Also Have Digestive Symptoms

For many years, gastrointestinal symptoms in hypermobile individuals were viewed as separate issues. Today, researchers increasingly recognize that autonomic dysfunction may be one of the major factors linking hypermobility and digestive complaints.

The autonomic nervous system helps regulate movement throughout the digestive tract. When autonomic signaling becomes disrupted, patients may experience:

• Reflux
• Nausea
• Early fullness
• Bloating
• Constipation
• Diarrhea
• Abdominal pain
• Delayed stomach emptying (gastroparesis)

The Ehlers-Danlos Society notes that gastrointestinal symptoms are common in both hypermobile EDS and Hypermobility Spectrum Disorders and can significantly impact quality of life. Researchers have identified important relationships among hypermobility, disorders of gut-brain interaction, gastrointestinal dysmotility, and autonomic dysfunction.

For many patients, understanding this connection can be profoundly validating. Digestive symptoms may not be isolated problems but rather another expression of the same underlying physiologic processes affecting multiple body systems.

Why Understanding the "Why" Matters

As a naturopathic doctor, one of the most important lessons I have learned from caring for patients with hypermobile Ehlers-Danlos syndrome and Hypermobility Spectrum Disorders is that symptoms rarely exist in isolation.

Patients may arrive carrying diagnoses from multiple specialists—POTS, IBS, chronic constipation, migraines, bladder dysfunction, chronic fatigue, mast cell activation syndrome, anxiety, or chronic pain—yet still feel that no one has connected the dots.

One of the core principles of naturopathic medicine is Tolle Causam—identify and address the cause. Another is to treat the whole person rather than focusing on individual symptoms or organ systems.

While we do not yet have all the answers regarding dysautonomia in hEDS and HSD, understanding the underlying physiologic mechanisms helps us move beyond symptom management and toward a more comprehensive understanding of why these seemingly unrelated symptoms may occur together.

The better we understand the "why," the better equipped we are to support patients living with these complex conditions.

What New Research Is Teaching Us

One of the most significant developments in recent years comes from a 2025 study by Novak and colleagues that evaluated 270 individuals with hypermobile Ehlers-Danlos syndrome using comprehensive autonomic, neurologic, and cerebrovascular testing.

The researchers identified several important findings, including:

• Evidence of widespread autonomic dysfunction
• Reduced cerebral blood flow when standing
• Frequent symptoms of cerebral hypoperfusion, including dizziness and brain fog
• High rates of small fiber neuropathy
• Evidence of cerebrovascular dysregulation

The authors concluded that hypermobile EDS is associated with measurable cerebrovascular, autonomic, and neuropathic abnormalities rather than simply representing a musculoskeletal condition.

These findings are important because they provide objective physiologic evidence supporting what many patients have reported for years—that their symptoms extend far beyond joint hypermobility alone.

At the same time, this study raises as many questions as it answers. Researchers are still working to determine whether small fiber neuropathy is a primary driver of dysautonomia, whether connective tissue abnormalities initiate the process, how mast cell activation fits into the picture, and why some individuals are significantly more affected than others.

While much remains to be learned, the field is moving rapidly toward a more integrated understanding of the relationship between connective tissue, the autonomic nervous system, circulation, immune signaling, and gastrointestinal function.

Looking Beyond the Joints

Historically, hypermobility disorders were viewed primarily through a musculoskeletal lens. Increasingly, however, research suggests that for many patients, these conditions are far more systemic.

The emerging picture is one of a complex, multisystem condition involving connective tissue, the autonomic nervous system, immune regulation, gastrointestinal function, and potentially small nerve fiber integrity.

While researchers are still working to understand exactly how these systems interact, it is becoming increasingly clear that dysautonomia may represent one of the key threads connecting many of the symptoms experienced by individuals with hypermobile EDS and Hypermobility Spectrum Disorders.

For patients who have spent years searching for answers, that recognition matters.

Understanding the underlying mechanisms does not solve every problem, but it provides a framework for more targeted evaluation, more personalized treatment approaches, and perhaps most importantly, validation that these symptoms are real, interconnected, and worthy of further investigation.

The more we learn, the more connected these systems appear to be.

And perhaps most importantly, the more we understand these connections, the better positioned we are to provide meaningful, individualized care for the people living with them.

References

Novak P, et al. Cerebrovascular, autonomic and neuropathic features of hypermobile Ehlers-Danlos syndrome. 2025.

The Ehlers-Danlos Society. Gastrointestinal Problems in Hypermobile Ehlers-Danlos Syndrome and Hypermobility Spectrum Disorders.

About the Author

Dr. Sarah Giardenelli, ND, MSOM, LAc is a naturopathic doctor, licensed acupuncturist, and founder of Collective Health Center in Leesburg, Virginia. She specializes in helping individuals with complex chronic health conditions uncover the root causes contributing to their symptoms through an integrative, evidence-informed approach.

Over the years, Dr. Giardenelli has worked with many individuals living with hypermobile Ehlers-Danlos syndrome, Hypermobility Spectrum Disorders, dysautonomia, mast cell activation syndrome, chronic gastrointestinal dysfunction, and related complex chronic illnesses. These patients have been some of her greatest teachers.

"The more I work with individuals living with hypermobility disorders, the more I appreciate how interconnected the body's systems truly are. Their experiences continually challenge us to think beyond isolated symptoms and to look deeper at the relationships between connective tissue, the nervous system, immune function, circulation, and gastrointestinal health. They remind us that good care begins with listening, curiosity, and a willingness to keep learning." ~Dr. Sarah

Medical Disclaimer

This article is intended for educational purposes only and is not a substitute for individualized medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional regarding questions about your health.