People who suffer from narcolepsy may experience hallucinations just like those people under LSD see. This type of imaginary visions is called hypnagogic hallucinations. They appear and go unintentionally, without any specific reasons. Their shape depends on what the person is having on a mind. This symptom takes place when the individual is trying to fall asleep or, vice versa, get up. As a rule, these images are vivid and terrifying as the patient is half way to awakening. It seems like the person starts having dreams and takes them as a real world.