Heat syncope is fainting as a result of overheating (syncope is the medical term for fainting). It is another stage in the same process as heat stroke, it occurs under similar conditions, and it is not distinguished from the latter by some authorities. The basic symptom of heat syncope is a body temperature above 40°C (104°F) with fainting, with or without mental confusion

Mental confusion

Confusion of a pathological degree usually refers to loss of orientation sometimes accompanied by disordered consciousness and often memory Confusion (from Latin confusĭo, -ōnis, noun of action from confundere "to pour together", also "to confuse") of a pathological degree usually refers to loss...

, which does occur in heat stroke. Heat syncope is caused by mild overheating with inadequate water or salt. In young persons, it is far more common than true sunstroke.

Causes

Heat syncope occurs when blood pressure

Blood pressure

Blood pressure is the pressure exerted by circulating blood upon the walls of blood vessels, and is one of the principal vital signs. When used without further specification, "blood pressure" usually refers to the arterial pressure of the systemic circulation. During each heartbeat, BP varies...

 is lowered as the body dilates (widens) arterioles (small blood vessel

Blood vessel

The blood vessels are the part of the circulatory system that transports blood throughout the body. There are three major types of blood vessels: the arteries, which carry the blood away from the heart; the capillaries, which enable the actual exchange of water and chemicals between the blood and...

s) in the skin to radiate heat. Also, water is evaporated from the blood, reducing the blood's volume and therefore lowering blood pressure further. The result is less blood to the brain, causing light-headedness and fainting.

Treatment

The basic treatment for heat syncope is like that for other types of fainting: the patient is positioned in a seating or supine position

Supine position

The supine position is a position of the body: lying down with the face up, as opposed to the prone position, which is face down, sometimes with the hands behind the head or neck. When used in surgical procedures, it allows access to the peritoneal, thoracic and pericardial regions; as well as the...

with legs raised. Water is administered slowly, and the patient is moved to a cooler area.