Your insomnia could be caused by any number of reasons. Acute insomnia can come and go in periods lasting for up to several weeks and can usually be attributed to a lifestyle change that is related to stress, diet or a recent medical condition. Chronic insomnia is insomnia that persists for longer than a month and can even be lifelong. Psychological disorders or a state of hyperarousal can also cause paradoxical insomnia that may occur for seemingly no reason at all.