Multitasking is really switching
Most of us think we can do several things at once. We read an article with a chat window open, or listen to a meeting while answering emails.
For simple, automatic tasks, this can be fine. You can walk and talk at the same time. But when two tasks both need real thought, your brain does not truly do them together. It switches back and forth between them, very quickly.
Every switch costs something. You lose a few seconds getting back into the first task. You may lose your place or your train of thought. Research suggests that this switching makes work slower and leads to more mistakes, even though it can feel efficient.
Remember the small desk of working memory? Each time you switch, you clear part of the desk. When you switch back, you have to set it all up again.
The pull of the phone
Phones are built to grab your attention. A buzz, a sound, a little red number. Each one invites you to check, and checking often turns into ten minutes of scrolling.
Even a silent phone can be a distraction if you can see it. Part of your mind is aware it is there and keeps wondering if something new has arrived. Resisting the urge to check also takes effort.
The simplest fix is distance. Put the phone in another room, in a bag, or at least face down and out of reach. Turn off notifications you do not need, or use a focus setting while you study.
One thing at a time
Single-tasking means choosing one task and giving it your full attention. Before you start, decide what that one task is. "Read chapter 3 and write a short summary" is clearer than "study".
Close tabs and apps you do not need. If a stray thought pops up, like "I need to buy milk", jot it on a notepad and come back to it later.
Short sessions work well
You do not need hours of perfect focus. Short, focused sessions are easier to start and easier to protect. A common approach is to work for about 25 minutes, then take a five-minute break. Some people prefer longer or shorter blocks. The exact number matters less than the pattern: focus fully, then rest.
During breaks, try to step away from screens. Stretch, get water, or look out a window.
Try it
Choose one small task you have been putting off. Put your phone in another room, close everything else on your screen, and set a timer for 15 minutes. Work only on that task until the timer ends. Then notice how much you got done.