Is A Heart Rate Of 45 Dangerous?

For most adults, a normal resting heart rate during the day ranges between 60 and 100 beats per minute. However, this can vary depending on factors such as physical fitness, emotional state, body position, and time of day. During sleep, it's common for the heart rate to drop below the typical daytime range due to increased activity of the parasympathetic nervous system, which slows the heart.

Nighttime Heart Rate And What's Normal

At night, when the body is at rest and the vagus nerve is more active, heart rates can naturally decrease. It's not unusual for a healthy individual's heart rate to fall as low as 35 beats per minute while sleeping. If a heart rate of 45 beats per minute occurs during the night, it's generally considered within the normal range and not a cause for concern.

Athletes And Lower Heart Rates

In the case of athletes or individuals who are highly physically active, a heart rate of 45 beats per minute during the day may also be completely normal. Regular endurance training improves cardiac efficiency, meaning the heart can pump more blood with each beat, reducing the need for a higher heart rate. This adaptation is a sign of a strong and well-conditioned cardiovascular system.

When To Seek Medical Advice

If a person who is not an athlete has a consistent daytime heart rate of 45 beats per minute and experiences symptoms such as dizziness, fatigue, shortness of breath, or fainting, it may indicate bradycardia—abnormally slow heart rate. In such cases, a healthcare provider may recommend a 24-hour Holter monitor to assess heart rate patterns throughout the day and night, including during physical activity and rest.

This monitoring helps detect any episodes of excessively slow or fast heartbeats and provides valuable data for a cardiologist to determine if further investigation or treatment is necessary. Ultimately, whether a heart rate of 45 is dangerous depends on the context—such as when it occurs, the individual's overall health, and whether any symptoms are present.