As reported by, a recent study in the journal Psychiatric Annals indicates that substance abuse is related to several types of sleep disorders such as insomnia, excessive sleep, sleep apnea, and daytime sleepiness. Substance abuse can affect neurotransmitters (brain chemicals) that are involved in normal sleep regulation. Sleep disturbances can also persist even after an individual abstains from substances, and these sleep disturbances can be a cause of drug relapse. To read more about this article, please click here.