You wake up, glance at your smartwatch, and notice something's off. Usually, your heart ticks along at a cool 62 beats per minute (bpm). Today? It’s sitting at 74. You haven't even had coffee yet. It’s a tiny shift, but it feels loud. Maybe you feel a slight flutter, or perhaps you just feel "heavy." If you're wondering why has my resting heart rate increased, you aren't alone. In fact, with the rise of wearables like Oura rings and Apple Watches, people are obsessing over these numbers more than ever.
It’s easy to spiral. We think: Am I out of shape? Am I getting sick? Is it something worse?
Honestly, your resting heart rate (RHR) is one of the most sensitive barometers your body has. It’s like a check-engine light that flickers long before the car actually breaks down. While a normal range for adults is typically between 60 and 100 bpm, your "normal" is specific to you. When that baseline shifts upward, your nervous system is likely reacting to a stressor—some obvious, some totally hidden.
The Stress Response Nobody Noticed
Stress isn't just "having a bad day at work." It’s physiological. When you're under pressure, your adrenal glands pump out cortisol and adrenaline. These hormones tell your heart to pick up the pace to prepare for a "fight or flight" scenario.
Even if you’re just sitting at a desk answering emails, your body might think you’re running from a predator. This keeps your sympathetic nervous system in the driver's seat. If you haven't been sleeping well or you're constantly "on," your RHR will climb. It's essentially your body's way of saying it has no time to recover.
Overtraining and the Fatigue Trap
Athletes often see an increased RHR as the first sign of overtraining syndrome (OTS). You might think more exercise equals a lower heart rate. Usually, that’s true. But if you hit the gym too hard without enough rest, your parasympathetic nervous system—the "rest and digest" side—shuts down.
I've seen runners ignore a 10-beat jump in their morning RHR only to end up with a stress fracture or a month of burnout. It’s a classic mistake. If your heart is working harder while you're literally doing nothing, it has no resources left to help you PR your next 5k.
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Why Has My Resting Heart Rate Increased? The Stealth Culprits
Sometimes the reason is sitting right in your cup. Or your pharmacy cabinet.
Dehydration is a massive, underrated factor. When you’re dehydrated, your blood volume actually drops. Think of it like a pump trying to move thick sludge through pipes instead of water. To keep your blood pressure stable and get oxygen to your brain, your heart has to beat faster. Even 1% or 2% dehydration can spike your RHR significantly.
Then there's the stuff we ingest.
- Caffeine: This one is obvious, but the half-life is longer than you think. That 4 p.m. espresso is still in your system at 10 p.m.
- Alcohol: This is the big one. Alcohol is a toxin that triggers an immediate inflammatory response. It’s notorious for spiking RHR during sleep. If you have two glasses of wine, don't be surprised if your RHR is 10-15 bpm higher all night.
- Medications: Decongestants containing pseudoephedrine are basically stimulants. Thyroid medications or even certain asthma inhalers can also send your numbers north.
The "Incubation" Phase: Are You Getting Sick?
One of the coolest (and scariest) things about tracking RHR is that it can predict an illness before you feel a single sniffle.
When your immune system detects a virus or bacteria, it starts mounting a defense. This requires energy. Your metabolic rate increases, and your heart rate follows suit to transport white blood cells and nutrients. Researchers at Stanford University found that wearables could detect COVID-19 and other respiratory infections days before symptoms appeared just by looking at RHR deviations.
If your heart rate is up but you feel fine, check your temperature. You might be fighting off a cold you didn't even know you had.
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When to Actually Worry About Your Heart Rate
Most of the time, a higher RHR is lifestyle-related. But we have to be real: sometimes it’s clinical.
Anemia is a common culprit. If you don't have enough iron or red blood cells to carry oxygen, your heart has to compensate by pumping more frequently. You’ll usually feel this alongside fatigue and shortness of breath.
Thyroid issues are another big player. An overactive thyroid (hyperthyroidism) acts like an internal gas pedal, revving up every system in your body, including your pulse. If you're losing weight without trying or feeling shaky, this is something to talk to a doctor about.
Then there’s Arrythmia. If your heart rate isn't just high, but feels "jumpy" or irregular, it could be Atrial Fibrillation (AFib). While many people live with AFib, it does require medical management to prevent stroke risks.
The Role of Poor Sleep and Circadian Disruption
Sleep isn't just "off time." It's when your heart rate is supposed to hit its lowest point—the "nadir."
If you have sleep apnea, you might be stopping breathing dozens of times a night. Every time you stop breathing, your oxygen drops, and your brain sends a panic signal to your heart to beat faster to save you. People with undiagnosed sleep apnea often wake up with an elevated RHR and a headache. Even just basic sleep deprivation—getting 5 hours instead of 8—keeps your blood pressure and heart rate elevated the next day because your body stays in a state of high alert.
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How to Bring Your Numbers Back Down
You can actually influence these numbers. It's not just "luck."
- Prioritize Magnesium: Most people are deficient. Magnesium helps the heart's electrical system stay stable and supports the parasympathetic nervous system.
- The "Slow" Cardio Fix: We spend too much time in "Zone 3"—that middle ground where we're huffing but not sprinting. True Zone 2 training (easy enough to have a full conversation) strengthens the heart's stroke volume. A stronger heart pumps more blood per beat, meaning it has to beat less often.
- Breathwork: It sounds "woo-woo," but it’s biology. Long, slow exhales stimulate the vagus nerve. This is the direct "brake" for your heart.
- Hydration with Electrolytes: Water alone isn't always enough. If you’re sweating or drinking coffee, you need sodium and potassium to keep the electrical signals in your heart firing correctly.
Practical Next Steps for You
If you've noticed a trend where your resting heart rate is consistently 5-10 beats higher than it was a month ago, don't panic, but do take action.
First, audit your last 48 hours. Did you drink alcohol? Did you sleep poorly? Are you feeling more "tight" in your chest or shoulders than usual? If the answer is yes, take three days of "radical recovery." No intense exercise, no booze, and an extra hour of sleep.
Second, check for trends, not outliers. One high reading doesn't mean anything. A seven-day average that keeps climbing is what matters.
If the elevation persists for more than two weeks despite resting—or if you experience dizziness, chest pain, or fainting—get a blood panel done. Specifically, ask for your ferritin (iron stores), TSH (thyroid), and a basic CBC.
Your heart is a high-performance engine. It's incredibly resilient, but it doesn't like being red-lined for no reason. Listen to the rhythm. Usually, the answer to why has my resting heart rate increased is simply that your body is asking for a break. Give it one.