The most effective method to restore alertness is sleep. If there is not enough time for a full cycle (1.5-2 hours) of sleep, a 20-minute sleep will do. It is advisable to take a nap in a quiet and dark room, or wear an eye mask and open the window for fresh air. By the way, even the fact that you just lie down for 20 minutes and give your eyes a rest will help to cheer up a little.
If there is no time for even a short break, try some folk tips:
We have collected a few more tips in our Zen article "What to do if you want to sleep at work".
Drink grapefruit juice until full enlightenment.
Especially if you have to drive tired.
No, not coffee.
It is grapefruit, not orange.
Because it is still nasty and when you drink it, at the same time it distorts you.