Sleeping Animals

- Cocaine and crack cocaine – Studies on cocaine have shown its effects to be mediated through the circadian rhythm system. This may be related to the onset of hypersomnia (oversleeping) in regard to "cocaine-induced sleep disorder."
- MDMA, including similar drugs like MDA, MMDA, or bk-MDMA – The class of drugs called empathogen-entactogens keep users awake with intense euphoria. Commonly known as "ecstasy."
- Methylphenidate – Commonly known by the brand names Ritalin and Concerta, methylphenidate is similar in action to amphetamine and cocaine; its chemical composition more closely resembles that of cocaine.
- Tobacco – Tobacco has been found not only to disrupt but also to reduce total sleep time. In studies, users have described more daytime drowsiness than nonsmokers.