An irrational fear of being alone is called monophobia. Many individuals experience this phobia and show extreme insecurity, anxiety, and depression when left alone. As a result, they avoid such situations to a great extent. However, when such a situation arises they might experience dizziness, nausea, inability to distinguish between reality and unreality, lightheadedness, fear of fainting, and chest pain. A negligible percentage of people actually suffer from this phobia.