Your brain needs exercise just like a muscle. If you use it often and in the right ways, you will become a more skilled thinker and increase your ability to focus. But if you never use your brain, or abuse it with harmful chemicals, your ability to think and learn will deteriorate.
othing makes it harder to concentrate than sleep deprivation. You’ll be most rejuvenated if you go to bed early and don’t sleep more than 8 hours.
If you have the opportunity, take 10-20 minute naps when you are hit with a wave of drowsiness. Anything longer will make you lethargic, but a short nap will refresh you.