3. Splash some cold water on your face
This might sound extremely uncomfortable, especially in winter, but ice-cold water on your face works similarly to the concept of cooling your brain. However, sticking your face in freezing water also gives your nervous system a “shock-and-relax” response which makes you feel sleepy. The best way to do this is to fill your sink or a large bowl the ice-cold water and dunking your head into it for as long as you can tolerate it. You are guaranteed to feel sleepy almost immediately.