Anger is a healthy emotion like crying or laughing. If someone is angry, the cause of irritability can be because they are disappointed, scared, offended or feel hurt. However, if you find the closest person is overly angry, first investigate whether he is under the influence of treatment or suffering from an illness.
Dr. Helen Stokes Lampard of the Royal College of General Practitioners said, there are a number of medical conditions and drugs that cause emotions

Surely,

The biological Phenomenon

Due to imbalance of Hormones.

It also depends on Your Surroundings.

& your conciousness.

bad hormone balance