Do website blockers and focus apps actually work?

Focus apps, site blockers and screen-time limits are a large industry built on an untested premise: that removing the option to get distracted will make you more focused and happier. In 2025 a randomised controlled trial tested a strong version of that premise, and the results are more interesting than either the app marketing or the sceptics would suggest.

The intervention worked. Most people could not stick to it. Both halves matter.

The trial

Researchers ran a month-long randomised controlled trial in which participants installed an app that blocked all mobile internet from their smartphones for two weeks. The design was deliberately targeted: it blocked the feature that makes smartphones “smart” (mobile internet) while allowing participants to maintain mobile connection (through texts and calls) and nonmobile access to the internet (e.g. through desktop computers).

So this was not a digital detox. Participants kept their laptops, their email and their phone as a phone. What went away was the always-available internet in their pocket.

The effect on usage was large. Average screen time decreased in the Intervention group from 314 min at T1 to 161 min at T2, roughly halving daily phone use.

What improved

Three outcomes were measured: mental health, subjective well-being and attention, the last using an objective sustained-attention task rather than self-report.

All three moved. The intervention improved mental health, subjective well-being, and objectively measured ability to sustain attention; 91% of participants improved on at least one of these outcomes. Breaking that down, roughly 70% reported improved mental health, 73% experienced greater well-being, and roughly 59% showed better focus and attention.

The mechanism was not mysterious, and it was measured. When people did not have access to mobile internet, they spent more time socializing in person, exercising, and being in nature. They also slept about 18 minutes more each night.

That is the part worth underlining for anyone buying a focus app: the benefit came from what filled the gap, not from the blocking itself.

The compliance problem

Here is the finding the app industry does not advertise. Of the 467 who committed to blocking mobile internet for 2 weeks, 266 set up the app required to do so and 119 (25.5% of those who committed) met our preregistered definition of “compliant”.

Read that again. Three-quarters of people who volunteered for a study, agreed to the intervention and were being paid attention to could not keep a blocker running for ten days out of fourteen.

To the researchers’ credit, they analysed everyone regardless of compliance, which means the reported benefits include all the people who gave up. They also noted that even those who did not fully comply with the intervention experienced significant, though more modest, improvements.

There is a further signal about durability. Screen time rebounded once the block ended, climbing back to 265 minutes at the final measurement. The tool works while it is on.

What this means for a desk worker

The evidence supports a specific and slightly deflating conclusion: blocking works when it actually blocks, the effect size on wellbeing is meaningful, and your main obstacle is that you will turn it off.

Three practical implications follow.

Friction matters more than intention. The trial did not ask people to use their phones less; it removed the capability. Blockers with an easy off switch are closer to a reminder than an intervention.

Target the right thing. The trial blocked mobile internet specifically, leaving calls, texts and desktop internet alone. That is a more precise intervention than a blanket detox and probably why it was tolerable at all.

Have a replacement. The measured gains came through time reallocated to people, exercise and outdoors. A blocker with nothing to fill the space is likely to be an exercise in willpower rather than a change in life.

What the study does not show

It was two weeks, with one short follow-up, so nothing is known about months or years. Participants were volunteers who wanted to reduce phone use, which is not everyone. And the outcomes, apart from the attention task, were self-reported by people who knew exactly which condition they were in, so expectation effects cannot be excluded.

Common questions

Do focus apps and website blockers actually improve productivity?

The trial measured attention, mood and wellbeing rather than work output, and all three improved. No trial has shown blockers increase measured productivity.

How much does blocking phone internet help?

In the trial, 91% of participants improved on at least one of mental health, wellbeing and sustained attention, with roughly 70% reporting better mental health and 59% showing better attention.

Why do blockers stop working?

Mostly because people stop using them. Only 25.5% of those who committed to the two-week block met the compliance definition, and screen time rebounded after the intervention ended.

Is it better to block apps or the whole internet?

The tested version blocked mobile internet while leaving calls, texts and desktop access alone, which halved screen time while keeping the phone usable. That targeted approach is what the evidence covers.

The bottom line

Blocking the internet on your phone for two weeks measurably improved attention, mood and mental health in a randomised trial, largely by pushing people towards people, exercise and sleep. The catch is that three-quarters of willing volunteers could not keep the block running, so choose a tool that is genuinely hard to disable and decide in advance what the reclaimed hours are for.