Insomniacs have difficulty falling or staying asleep and researchers have found that various personality traits increase the chance of having this disorder. The research shows that introversion, perfectionism, neuroticism, hysteria, schizotypal, and borderline traits are associated with insomnia. Of course, this begs the question of why these traits lead to insomnia. Some psychologists think that emotional sensitivity in these traits leads to hyperarousal which then makes it hard to shut off their minds and sleep.
Introverts are especially vulnerable to hyperarousal which is why they find social interactions tiring. They tend to become overstimulated by the environment and that can make it difficult to fall asleep if there are distracting noises or if their minds are still active. Perfectionists also suffer from overactive minds in that they may obsess over mistakes they have made or think they will make. People who are perfectionistic also can be workaholics and work late which affects sleep as well.