Doing one thing at a time
Doing one thing at a time means giving a single task your attention until it is done or you deliberately stop, instead of switching between many. It is harder than it sounds, especially with ADHD, because everything competes for attention at once. The fix is usually not more willpower but fewer visible options.
Why switching costs so much
Every time you switch tasks, a bit of attention stays stuck on the one you left, so you are never fully on the new thing. Those open loops pile up, and for a brain that already struggles to hold things in working memory, a screen full of half-started tasks is exhausting rather than restful.
Researchers have a name for this: attention residue. In a 2009 study, Sophie Leroy found that when you move from one task to another, part of your attention stays behind on the first, and the effect is strongest when that task was unfinished or under time pressure. The residue does not clear on its own between switches; it stacks. That is why a morning of jumping between things can leave you drained with little to show for it, even though you were busy the whole time.
Multitasking is mostly fast switching
It helps to be honest about what multitasking really is. Outside of automatic things like walking and talking, the brain does not run two focused tasks at once; it switches between them quickly, paying that residue cost each time. So 'I work better with everything open' usually means 'I switch faster', not 'I focus on more'. The felt busyness is real; the extra output mostly is not. For a brain that finds switching especially costly, which includes many people with ADHD, the gap between feeling busy and getting things done can be wide.
Make the current thing the only thing
You cannot force focus, but you can remove competition for it. A few things that help many people:
- Show one task, not the list. Put the thing you are on where you will see it and hide the rest until it is done.
- Time-box it. Agree to stay on it for one short block, then decide. A boundary makes staying easier than an open-ended stretch.
- Body double. Working next to someone, in person or on a call, borrows their steadiness and makes wandering off more obvious.
What a single-task app does, and does not
A single-task app is just a tool that shows you one thing at a time and keeps the rest out of view, so the current task is not competing with a full list. That is the whole idea, and it is a small one; a sticky note or a closed door does the same job. An app mainly helps because your phone is where the distractions live, so a focus task on the lock screen meets the competition on its own ground.
NanoDo works this way: your top task sits on your lock screen, and the rest of the day waits out of sight until it is done. It is one way to make single-tasking the default, not a treatment and not the only way. If a paper list or a timer keeps you on one thing better, use that. The goal is one thing at a time, not a particular app.
This article is general information, not medical advice or a diagnosis. If task paralysis or focus is affecting your daily life, a doctor or an ADHD specialist can help.