Resting Heart Rate: What’s Sleep Got to Do with It?

If you’ve ever glanced at your fitness tracker first thing in the morning and thought, “Huh, why’s my resting heart rate higher today?” — you’re not alone. Resting heart rate (RHR) is one of those stats that sounds simple but turns out to be surprisingly insightful. It reflects what’s been going on with your body behind the scenes, from stress and illness to training load… and yes, sleep. Lots of it. 

So, what does sleep have to do with your resting heart rate, and why does it matter? Let’s dig a bit deeper and find out. 

First things first: what is resting heart rate? 

Your resting heart rate is basically how many times your heart beats per minute when you’re properly at rest — not scrolling, not stressing, not sprinting for the bus. For most people, that’s measured when you’re asleep or just waking up. 

In general (very general), a lower resting heart rate tends to suggest your heart is doing its job efficiently. Athletes often have lower RHRs because their hearts are well trained (1). A higher RHR can mean lots of things: fatigue, dehydration, stress, illness, or simply that your body’s had a rough night (2). 

And that’s where sleep comes in. 

Sleep is when your heart gets a breather 

When you fall asleep, especially during deep sleep, your body switches into repair mode. Your nervous system calms down, stress hormones drop, and your heart rate naturally slows. 

Think of it like this: during the day, your heart’s dealing with emails, deadlines, exercise, caffeine, emotions, and whatever else life throws at you. At night, sleep is its chance to put its feet up. 

Good-quality sleep gives your cardiovascular system time to reset. Poor or short sleep? Your heart doesn’t get that same break. 

Short sleep = higher resting heart rate 

If you regularly skimp on sleep, your body stays in a more “alert” state for longer. Stress hormones like cortisol hang around, your nervous system stays slightly revved up, and your heart rate doesn’t drop as much overnight. 

The result? You wake up with a higher resting heart rate (3). 

One late night won’t ruin anything, but if poor sleep becomes a pattern, your RHR can creep up and stay there. Many people notice this clearly on wearables: a bad night’s sleep often shows up the next morning as a few extra beats per minute. 

It’s your body’s polite way of saying, “I’m still tired, actually.” 

It’s not just about hours — quality matters 

Eight hours sounds great on paper, but sleep quality is the real MVP here. 

If you’re tossing, turning, waking up loads, or sleeping lightly, your body may not spend enough time in deep sleep — the stage where heart rate is lowest and recovery really happens. 

Things that can mess with sleep quality include: 

• Stress or anxiety 

• Late-night scrolling 

• Alcohol (yes, even if it makes you sleepy) 

• Heavy meals close to bedtime 

• Inconsistent sleep times 

You might technically be “in bed” for ages, but your heart still doesn’t get the downtime it needs. 

Stress, sleep, and your heart are a trio 

Sleep and stress are deeply tangled. When you’re stressed, sleep suffers. When sleep suffers, stress gets worse. Your heart rate sits right in the middle of this loop. 

Poor sleep can make your body more sensitive to stress the next day, pushing your heart rate up even when you’re not doing much. That’s why after a bad night, everything feels a bit harder — including exercise, concentration, and mood. 

On the flip side, improving sleep can help calm your nervous system, which often brings resting heart rate down over time. 

Training, recovery, and sleep 

If you exercise (especially running, cycling, gym sessions, or team sports), sleep becomes even more important. 

Training puts stress on the body — good stress, but still stress. Sleep is when the benefits actually happen: muscles repair, energy stores refill, and your heart adapts. 

When sleep is poor: 

• Recovery slows down 

• Fatigue builds 

• Resting heart rate may rise 

• Workouts feel harder than usual 

Many athletes use resting heart rate as a rough recovery check. If it’s higher than normal for a few mornings in a row, it can be a sign you need more rest — and often, more sleep. 

Illness and sleep disruptions 

Ever noticed your heart rate jump when you’re coming down with something? Even before obvious symptoms, your body’s immune system ramps up, which can raise your resting heart rate. 

Sleep often gets lighter or more restless at the same time, creating a double hit: less recovery and more internal stress. Again, your heart rate notices. 

This is one reason wearables sometimes spot changes before you feel properly ill — they’re picking up on how your body behaves during sleep. 

Can better sleep lower your resting heart rate? 

For many people, yes — gradually. 

You’re unlikely to see instant results after one early night, but consistent, decent sleep can help bring resting heart rate down over weeks or months. It’s not about perfection; it’s about patterns. 

Helpful habits include: 

• Going to bed and waking up at roughly the same time 

• Keeping the bedroom dark, quiet, and cool 

• Limiting caffeine later in the day 

• Putting your phone down before bed (annoying but effective) 

• Letting yourself properly wind down before bed 

None of this is groundbreaking, but it works because your heart likes routine almost as much as you do. 

Don’t obsess over the number 

One important note: resting heart rate is a trend metric, not a judgement. 

It naturally varies from day to day. A higher number doesn’t mean you’ve failed at health, and a lower one doesn’t make you invincible. It’s just data — useful when you look at it over time and in context. 

If your RHR jumps after a terrible night’s sleep, that’s normal. If it settles again once your sleep improves, that’s your body doing exactly what it should. 

So… what’s sleep got to do with it? 

Pretty much everything. 

Sleep is when your heart slows down, recovers, and resets. When sleep is short, broken, or stressful, your heart works harder — even during resting times. When sleep is consistent and good quality, your heart rate tends to reflect that calm. 

You don’t need to track every minute or chase the “perfect” number. Just remember: if you want a happier resting heart rate, start by giving your body the rest it’s quietly asking for. 

Sometimes the most effective health upgrade really is just going to bed. 

Sources: 

1. https://www.healthline.com/health/athlete-heart-rate 

2. https://www.bhf.org.uk/informationsupport/how-a-healthy-heart-works/your-heart-rate 

3. https://www.sleepfoundation.org/sleep-deprivation/how-sleep-deprivation-affects-your-heart