Heart rate 43 on an adult - what does it mean?

Where 43 bpm sits on the adult scale

What a resting pulse of 43 means

Endurance training makes the heart muscle stronger, so it moves more blood per beat and needs fewer beats at rest. Runners, cyclists and swimmers commonly rest between 40 and 60 bpm. During sleep, almost everyone's heart rate drops 10–20 bpm below the daytime resting value.

If you are not particularly fit, possible causes include medications (beta blockers and other heart-rate-lowering drugs), an underactive thyroid (hypothyroidism), sleep apnea and conduction problems of the heart. These are easy to check with an ECG and a blood test, or a sleep study for sleep apnea.

Ranges apply to adults and children aged 10 and older, measured at rest (American Heart Association). By the numbers: at 43 bpm the heart beats about every 1.40 seconds — roughly 61,920 beats a day.

A night-time 43 that keeps bouncing up and down

If your watch shows the pulse dipping to around 43 during the night and then jumping up again, over and over, sleep apnea is worth considering. In obstructive sleep apnea the throat repeatedly narrows or closes during sleep. Breathing stops or becomes very shallow for ten seconds or more, oxygen levels fall, and the brain briefly rouses you to restart breathing, usually without you remembering it.

The heart follows these events. During a pause, the rate often slows. When breathing restarts with a gasp, a burst of stress hormones speeds it up. The result on a graph is a saw-tooth pattern rather than the smooth night-time curve most people have.

Signs that point toward apnea

• loud, regular snoring, often worse lying on the back
• a partner noticing pauses in breathing, choking or gasping
• waking unrefreshed, with a dry mouth or a morning headache
• daytime sleepiness, such as dozing while reading or as a passenger
• waking often at night to urinate
• high blood pressure that is hard to control

Risk rises with excess weight, a large neck, older age, male sex, alcohol in the evening and sedative medicines. Slim people and women get it too, so do not rule it out on looks alone. Some people with apnea have the opposite problem in the daytime: a slightly raised resting rate from broken sleep.

Getting tested and why it is worth it

Diagnosis is made with a sleep study, either a home test that records breathing, oxygen and pulse, or a full overnight study in a sleep lab. The common treatment is CPAP, a mask that keeps the airway open with gentle air pressure. Oral devices, weight loss and sleeping on the side help some people.

Untreated apnea is linked with high blood pressure, atrial fibrillation and other heart problems, and with daytime accidents from sleepiness. In many people the slow night-time dips settle once breathing is treated.

Take screenshots of several nights of heart-rate graphs and, if your device records it, blood oxygen, to your appointment. If your waking resting rate is also in the low 40s and you are not an endurance athlete, ask for an ECG too. Notes on reading overnight wearable data are on the heart rate monitors page.

For a reliable resting value, sit quietly for five minutes first and average a few mornings: Resting Heart Rate: What It Says About Your Health. You can also measure by tapping along on the start page.

Nearby values

• 38 bpm
• 39 bpm
• 40 bpm
• 41 bpm
• 42 bpm
• 44 bpm
• 45 bpm
• 46 bpm
• 47 bpm
• 48 bpm

Measured on a child instead? See heart rate 43 in a child.

Sources: American Heart Association: All About Heart Rate · MedlinePlus: Pulse · ACSM position stand on exercise intensity (2011)

This page explains a single reading in general terms. It is not a diagnosis. Heart rate alone cannot tell whether the rhythm is regular or whether the heart is healthy — if you are worried, talk to a doctor.