Sedation

Sedation is a drug-induced state of reduced alertness and responsiveness, ranging from mild drowsiness to deep unresponsiveness, that differs from natural sleep.

Clinicians describe levels of sedation from minimal, in which a person is relaxed but answers normally, through moderate and deep, to general anesthesia, and they monitor it with scales such as the Richmond Agitation-Sedation Scale. As an intended effect, sedation is used before procedures and in intensive care. As a side effect, it is one of the most common adverse effects of medicines that act on the central nervous system, including benzodiazepines, opioids, antihistamines, antipsychotics, antiseizure medications and alcohol, and it is amplified when these are combined.

Sedation is distinct from somnolence, which is sleepiness that may or may not be drug-related, and from fatigue, which is exhaustion without necessarily dozing. Its practical consequences are impaired reaction time, coordination and judgment, which is why driving and operating machinery are unsafe under any sedating substance. In cannabinoid research, sedation or somnolence is among the most frequently reported side effects of cannabidiol, especially at the higher amounts used in seizure trials and when taken with clobazam or other sedatives, and it is a hallmark of THC in people and in pets. Cannabinoids have been studied for sleep, but sedation is a side effect to be recorded, not evidence of benefit, and no cannabinoid has an approved use as a sleep aid.