What type of angina is characterized by chest pain that occurs during sleep?

Variant angina, also known as Prinzmetal's angina, is a specific type of angina that is characterized by episodes of chest pain that can occur at rest, often during sleep. This condition is typically caused by coronary artery spasm, which leads to temporary reduction of blood flow to the heart muscle, resulting in the characteristic pain.

This type of angina can be unpredictable and may not be triggered by physical exertion or stress, unlike stable angina, which typically arises during activity or emotional stress due to narrowed arteries. Unstable angina also presents with chest pain that occurs at rest but is usually more severe and may indicate a progression in coronary artery disease. The mention of hiatal hernia refers to a condition that can mimic or cause discomfort in the chest area, but it does not fit the classic presentation of angina. Therefore, the correct identification of variant angina is crucial as it involves understanding the unique circumstances under which this type of pain occurs, notably at rest or during sleep.