Heart Racing? Why Your "Gravity Sensor" May Be Glitching — and What to Do Next

A fast, pounding heart can feel alarming. One minute you're fine. The next, your heart is racing when you simply stand up, walk across the room, or even sit upright.

If this sounds familiar, your body's built‑in "gravity sensor" may not be working the way it should.

One possible reason is POTS (Postural Orthostatic Tachycardia Syndrome) — a condition that affects how your nervous system regulates heart rate and blood flow when you change positions.

Let's break down what that means, why it happens, and what medical next steps make sense.

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Your Body's "Gravity Sensor": How It's Supposed to Work

When you stand up, gravity pulls blood down into your legs and abdomen.

Your body instantly responds by:

• Tightening blood vessels
• Slightly increasing heart rate
• Keeping blood flowing to your brain

This process is controlled by your autonomic nervous system — the automatic part that manages heart rate, blood pressure, and digestion without you thinking about it.

In people with POTS, this system doesn't respond properly.

Instead of a small heart rate increase (10–15 beats per minute), the heart may jump 30 beats per minute or more within 10 minutes of standing — without a major drop in blood pressure.

That exaggerated response can cause symptoms that feel frightening, even when they are not immediately life-threatening.

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What Is POTS?

Postural Orthostatic Tachycardia Syndrome (POTS) is a disorder of autonomic nervous system regulation.

It's diagnosed when:

• Heart rate increases by 30+ beats per minute in adults (or over 120 bpm total) within 10 minutes of standing
• Symptoms have lasted at least 3–6 months
• There is no other condition that explains the symptoms (like dehydration, anemia, or thyroid disease)

POTS is more common in:

• Women
• Teens and young adults
• People after viral illness
• Individuals with autoimmune conditions
• Those with joint hypermobility disorders

It is a real, recognized medical condition — not anxiety, though anxiety can coexist.

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Common Symptoms of POTS

The hallmark symptom is a fast beating heart when upright. But many other symptoms may occur.

Cardiovascular Symptoms

• Rapid heartbeat (especially when standing)
• Palpitations
• Chest discomfort
• Lightheadedness
• Fainting or near-fainting

Brain and Energy Symptoms

• Brain fog
• Fatigue
• Difficulty concentrating
• Headaches

Whole-Body Symptoms

• Nausea
• Shakiness
• Exercise intolerance
• Cold or discolored hands and feet
• Excess sweating

Symptoms often improve when lying down.

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Why Does POTS Happen?

POTS isn't caused by just one thing. Research shows several possible mechanisms:

1. Blood Pooling

Blood collects in the lower body when standing. The heart speeds up to compensate.

2. Low Blood Volume

Some people with POTS have reduced circulating blood volume.

3. Autonomic Nerve Dysfunction

The nerves that control blood vessel tightening don't respond correctly.

4. Hyperadrenergic State

Some individuals produce excessive stress hormones like norepinephrine.

5. Autoimmune Triggers

In some cases, the immune system may affect autonomic receptors.

Often, more than one factor is involved.

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Could It Be Something Else?

Not every fast heartbeat is POTS.

Other medical causes must be ruled out, including:

• Thyroid disorders
• Anemia
• Dehydration
• Heart rhythm disorders (arrhythmias)
• Medication side effects
• Anxiety disorders
• Adrenal problems

If you're experiencing a fast beating heart and want help understanding what might be causing it, Ubie's free AI-powered symptom checker can guide you through your symptoms in minutes and suggest possible next steps before your doctor visit.

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When a Fast Heartbeat Is an Emergency

While POTS itself is usually not immediately life-threatening, a racing heart can sometimes signal something serious.

Seek urgent medical care if you have:

• Chest pain that spreads to arm, neck, or jaw
• Shortness of breath at rest
• Fainting without warning
• A heart rate consistently above 150–160 bpm
• New neurological symptoms (weakness, confusion, slurred speech)

When in doubt, err on the side of caution.

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How Doctors Diagnose POTS

A proper diagnosis requires medical evaluation. A doctor may:

Take a Detailed History

They'll ask about:

• When symptoms occur
• What makes them better or worse
• How long they've lasted
• Recent illness or stressors

Check Orthostatic Vitals

Heart rate and blood pressure are measured:

• Lying down
• Sitting
• Standing (over 10 minutes)

Order Tests

These may include:

• Blood work (to rule out anemia, thyroid issues)
• ECG (electrocardiogram)
• Echocardiogram
• Tilt table test (specialized test for autonomic function)

Diagnosis should always be made by a qualified healthcare professional.

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Treatment Options for POTS

There is no single cure, but many people improve with treatment.

Lifestyle First (Often Very Effective)

Doctors commonly recommend:

• Increased fluids (2–3 liters daily unless medically restricted)
• Increased salt intake (if appropriate)
• Compression stockings
• Gradual, structured exercise (starting recumbent)
• Avoiding prolonged standing
• Smaller, more frequent meals

Consistency matters. Improvement often takes months.

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Medications (When Needed)

If lifestyle changes aren't enough, doctors may prescribe:

• Beta blockers (to slow heart rate)
• Fludrocortisone (to expand blood volume)
• Midodrine (to tighten blood vessels)
• Ivabradine (in select cases)

Medication plans are individualized. Not everyone needs them.

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Can POTS Improve?

Yes.

Many people — especially younger patients — see significant improvement over time.

Some recover fully. Others learn to manage symptoms effectively.

Recovery often requires:

• Patience
• Consistent self-care
• Medical guidance
• Avoiding overexertion early on

It's not "all in your head," but it also isn't hopeless.

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Is It Anxiety — or POTS?

This is a common and frustrating question.

Anxiety can cause a racing heart.
POTS can also trigger anxiety-like symptoms.

Key differences:

• POTS symptoms are strongly position-dependent
• Heart rate increases are measurable and consistent
• Symptoms improve when lying down

That said, anxiety and POTS can coexist — and both deserve treatment.

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Practical Next Steps If Your Heart Is Racing

If you suspect POTS or another cause of tachycardia:

1. Track your heart rate lying down vs. standing.
2. Note triggers and symptom patterns.
3. Stay hydrated.
4. Avoid sudden position changes.
5. Schedule an appointment with a primary care doctor or cardiologist.

Bring your symptom log. It helps more than you think.

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The Bottom Line

A racing heart when you stand up is not something to ignore.

Sometimes it's dehydration.
Sometimes it's anxiety.
Sometimes it's POTS, a condition where your body's "gravity sensor" misfires.

While POTS is usually not immediately life-threatening, untreated symptoms can significantly impact quality of life. And other causes of tachycardia can be serious.

If your heart is frequently racing, fainting, or accompanied by chest pain or neurological symptoms, seek medical care promptly.

For persistent or unexplained symptoms, speak to a doctor. Proper evaluation is essential to rule out dangerous conditions and to create a treatment plan that fits your body.

Your heart may be beating fast — but with the right steps, you can slow the chaos and regain control.