Which of the following is NOT a correct option when investigating causes of sinus tachycardia?

In the context of investigating causes of sinus tachycardia, understanding the physiological responses of the body is crucial. Sinus tachycardia is characterized by an increased heart rate that typically occurs in response to various stimuli or conditions that require the body to enhance its cardiac output.

Anxiety is a well-documented factor that can increase heart rate. The body's stress response releases hormones like adrenaline, which can lead to an increase in heart rate, making anxiety a valid contributor to sinus tachycardia.

Caffeine, being a stimulant, is also known to raise heart rate. It acts primarily as an adenosine receptor antagonist, resulting in increased excitability of heart tissues, which can indeed lead to sinus tachycardia in individuals sensitive to its effects.

Exercise is another common cause of sinus tachycardia. During physical activity, the heart naturally pumps faster to meet the increased demand for oxygen and nutrients by the muscles, which manifests as an elevated heart rate.

Fatigue, on the other hand, is generally characterized by a decreased ability of the body to sustain prolonged physical effort and does not typically induce the same sympathetic nervous system activation as anxiety or exercise. While fatigue could potentially lead to other cardiovascular responses, it is not a typical direct