While on holidays, I've been putting a lavender oil mix in our ultrasonic oil diffuser . . . and wondering why I keep falling asleep.
Took awhile, but realised I was long enough into holidays to have recovered most of sleep deficit, and then thought - ah, oil!
Change of blend, and am feeling alert and able to do stuff :)
(Reminded me of someone I knew in the 80s who had a similar effect from chamomile tea - until her daughter pointed out the soporific effects of the tea.)