“Sometimes I just can’t stop yawning even when I’m not tired. Could this be a sign that something is wrong?”

In rare cases, excessive yawning could be a sign of a medical problem, such as heart disease, which can excessively stimulate the vagus nerve (that runs from the brain to the abdomen) and trigger yawning. Brain conditions, such as a tumor, stroke or multiple sclerosis, can also cause excessive yawning.

If you are around people who are yawning, chances are good you’ll yawn, too. Contagious yawning affects about half of adults, according to a recent study conducted at Duke University in Durham, North Carolina.

But yawning all the time usually means that you are more tired than you think you are. Research has shown that we tend to be poor judges of our level of alertness.

For example, in one study, sleep-deprived adults felt alert but took twice as long to correctly make decisions as those who were well rested.

Most adults need approximately seven to nine hours of nightly sleep for optimal daytime alertness. Be sure to make it a priority to get the amount of sleep that your body needs.

If you struggle to stay awake during the day, talk to your doctor about being tested for sleep apnea, a disorder in which the airway collapses during sleep, causing breathing to stop and start again. Frequent interruptions in breathing can interfere with sleep—and leave you feeling exhausted the next day.