Migraines affect 36 million people in the United States, which constitutes about 12 percent of the American population. One in seven people suffer from migraines every year. Yet, as common as they may seem, migraine attacks can be severe enough to last for several days, according to Medical News Today.

People who experience migraines are usually aware of the factors that trigger the attacks. However, there are some unexpected migraine triggers that catch many people off guard. Knowing what the triggers are can help you avoid them and may spare you from a debilitating headache.

Running can set off a migraine attack, but only if you are not used to regular aerobic activity. While regular exercise lessens the possibility and intensity of migraines, a sudden physical activity like running can trigger them, according to a study conducted at the Headache Center in Atlanta. To avoid and lessen migraines, a regular workout routine should be developed.

Lack of sleep is a known migraine trigger, but many people don't know that oversleeping can also lead to terrible migraine headaches. Oversleeping disrupts the circadian rhythm, which can set off a migraine attack, according to the Office on Women's Health at the U.S. Department of Health and Human Services. The key to keeping migraines at bay is to maintain a regular sleep pattern.

Stress is one of the common factors that cause migraines, but so is taking time to relax. Taking a break from a stressful period causes the level of cortisone to drop, resulting in a headache, according to a 2014 study published in the journal Neurology.

"Reduction in stress from one day to the next is associated with migraine onset the next day," wrote the study authors. "Decline in stress may be a marker for an impending migraine attack and may create opportunities for preemptive pharmacologic or behavioral interventions."

Although migraines have no cure, it can be managed. Knowing the common and not-so-common migraine triggers can help migraine sufferers adopt lifestyle changes in order not to trigger the condition.