Hypersomnia due to a medication or substance

This article focuses on sleepiness as a side effect of sedating drugs. Principal mechanisms for drug-induced sedation include inhibition of wake-promoting neurotransmitters (e.g., acetylcholine, dopamine, histamine, hypocretin/orexin, norepinephrine, serotonin) and/or activation of sleep-promoting processes (e.g., enhancement of gamma-aminobutyric acid (GABA) inhibition, inhibition of glutamate, enhancement of adenosine or melatonin). Drugs commonly associated with sedating side effects include a number of psychotherapeutic compounds, antiepileptic drugs, and drugs used in the treatment of pain. Drugs used in the treatment of insomnia may result in daytime sedation when pharmacological action extends beyond the sleep period.