I was warned that the drug could pass very quickly out of the ... I felt tired all the time, suffered from terrible nightmares and chronic insomnia. For Matthew's sake, I tried to be as normal ...

According to the DSM, nightmares are generally thought to be caused by anxiety or stress; trauma or an upsetting event; sleep disorders; a fluctuating sleep schedule; or medication or drug use.

American actor Nicolas Cage revealed how his life became a waking nightmare after he used drugs. He first became addicted in his twenties, after he started experimenting with hard drugs.