Yawning can be a response to anxiety and stress. When we are in a heightened state of tension, our body's natural response is to take deep breaths and increase oxygen intake. Yawning helps regulate breathing patterns and can serve as a subconscious mechanism to alleviate stress.

Excessive yawning reasons include: Physical Causes—Fatigue, general tiredness, body temperature malfunctions, and stimulation of the vagus nerve can cause frequent yawning. Excessive yawning and sleep disorders are often correlated. Emotional Causes—Anxiety and depression can lead to yawning excessively.

There's little evidence to suggest that excessive yawning is caused directly by a vitamin deficiency. However, some vitamin deficiencies may cause fatigue, which often involves yawning. Not getting enough vitamin B12, for example, can lead to vitamin B12-deficiency anemia, which may lead to feeling fatigued.