One of the signature symptoms of mania (and to a lesser extent, hypomania) is what many have described as racing thoughts. These are usually instances in which the manic person is excessively distracted by objectively unimportant stimuli. This experience creates an absent-mindedness where the manic individual's thoughts totally preoccupy him or her, making him or her unable to keep track of time, or be aware of anything besides the flow of thoughts. Racing thoughts also interfere with the ability to fall asleep.