As of 2014, researchers have yet to discover why some people feel bored with their lives. Common causal theories include the lack of external stimulation or the ability to acquire it, the difficulty of a task relative to the person, and depression.
Boredom, like other feelings, is a person's perception of stimulation interpreted through the senses. Some researchers believe boredom arises when a person can't interpret his feelings or desires, a phenomenon called alexithymia. Sufferers don't know much about what to do and have difficulties developing hobbies. Others postulate boredom is anger turned inwards. Anger and hostility are common amongst people claiming to be bored.
Because boredom is a subjective feeling that changes from one individual to another, discerning the cause of boredom is difficult. Life is full of repetitious actions that can lead to a sensation of redundancy. People who are bored are more likely to turn to drugs or alcohol.