Heat syncope (fainting or lightheadedness) usually occurs at the end of exercise. If you begin to feel faint, get out of the heat and rest in a cool, shady place. Lie down, elevate your legs, and drink cold water. Feeling faint or lightheaded can be an early warning sign of heat exhaustion; therefore, if you experience the symptoms, you should use extreme caution with further activity in the heat or you should avoid it completely.
Symptoms of heat syncope include:
• Pale, cool, and moist skin
Prevention is based on acclimatization and avoiding long periods of immobility. Acclimation also helps you remain active in a hot environment with less risk of heat- related illness. You can acclimate yourself to a hot environment by gradually increasing the amount of time you exercise in the heat each day.
Content Source: National Institute for Occupational Safety and Health (NIOSH)