Caffeine

- There's a very interesting body of research that suggests that caffeine does improve focus and memory and the ability to learn. So it seems to help us lock in memories. As for focus, it increases our ability to concentrate on a task, it's incredibly important for modern work. - And of course, caffeine also gives us a burst of energy, but how exactly? Coffee has less than five calories. - Caffeine seemed to be in violation of the laws of thermodynamics. Essentially, caffeine borrows energy from your future and gives it to you in the present. Caffeine occupies a receptor that normally is occupied by a chemical called adenosine, and this is the chemical that, over the course of the day, builds up and makes you feel tired and prepares the brain for sleep. Caffeine gets in there and blocks that receptor so you never feel that tiredness. - Right, and that's the catch. Caffeine messes with your sleep because four to six hours after you drink it, half of it is still swirling around in your body. - But even if you cut it out earlier in the day, the quality of your sleep may suffer. Not the quantity, necessarily, but the quality. By which, I mean your deep sleep, your slow wave sleep, a kind of sleep that's dreamless and very deep and is very important to kind of brain hygiene. That's where your brain kind of takes out the garbage every night and cleans up the desktop. And that kind of sleep suffers.