noun
stimulant effect; wakefulness-promoting action
Refers to the property of a substance (such as caffeine) that promotes alertness or counteracts drowsiness. Often used in medical, pharmacological, or everyday contexts.
コーヒーの覚醒作用で、夜遅くまで勉強できた。
Thanks to the stimulant effect of coffee, I was able to study late into the night.
この薬には強い覚醒作用があるため、就寝前の服用は避けてください。
This medicine has a strong wakefulness-promoting effect, so please avoid taking it before bedtime.
Compound of 覚醒 (かくせい, 'awakening') and 作用 (さよう, 'action, effect'). The term is straightforward and modern, with no obscure historical derivation.