I am not a doctor, nor a scientist. Just a street photographer with a hobby capturing anything with any camera, or in short a common person only.
However, I am confident that I know exactly about the best cure for sleepiness. My suggestion works in 99.9999% of the cases and whoever suffers from sleepiness will recover if they do follow my advice.
To me it’s clear as crystal that the best cure for sleepiness is only one thing, a sleep. Coffee may help someone to stay awake a bit longer but eventually he or she will still feel sleepy.
But, a sleep will help the sleepy person to feel fresh until the next round of sleepiness come which can be cured with the same manner.
You can try by yourself and definitely you will find my advice is very accurate even though I am not a doctor.