Which of the following is a symptom of vasovagal syncope?

Lightheadedness is a key symptom of vasovagal syncope, which is a common cause of fainting. This condition occurs when the body overreacts to certain triggers, such as stress, pain, or prolonged standing. During a vasovagal episode, the heart rate slows down, and blood vessels dilate, resulting in reduced blood flow to the brain. This often leads to feelings of lightheadedness or dizziness just before a person loses consciousness.

The other options listed do not align with the typical symptoms of vasovagal syncope. Increased appetite is generally not associated with this condition, nor is excessive sweating during activity, which is more related to heat or physical exertion rather than a vasovagal response. Chronic fatigue, while a concern for many, is not a specific symptom of vasovagal syncope either. Thus, lightheadedness is the most relevant and accurate symptom associated with this condition.