However busy you might be, it’s all-too-easy to waste time checking Facebook, Twitter, YouTube, and many other distracting domains.

Browser add-ons can help you block these sites, but they’re often too restrictive. Limiting access is good, but if they go too far you’ll just uninstall them in a day or two and carry on as before.

Morphine is a free Chrome distraction-blocker which keeps you away from the most time-sucking sites, while also giving you the flexibility to take occasional breaks.

Setup starts by manually entering your most time-wasting domains: facebook.com, youtube.com or whatever they might be. There’s no “Add this site” mouse-click option, you must enter each one manually.

Every domain you’ve specified is immediately blocked, with no “emergency exception” links or other easy ways around the protection.

A panel displays the time you’ve earned and allows you to take very brief breaks

Carry on working for 10 minutes, though, and Morphine will give you one minute to access sites on the blocked list. This allowance builds up over time – 2 free minutes after 20 minutes work, 3 after 30 – and you can use some or all of your allowance whenever you need a quick break.

These figures are only defaults, and may be tweaked if you like. You might decide to have a 30-minute minimum work time, for instance, but then reward yourself with a 5-minute allowance.

This is much more practical for real-world use than most of the competition. You don’t have to set up some fixed schedule for work and break time, which hardly ever fits what you’re really doing– Morphine is ready to do its job at any time of day.

It’s also not too restrictive, as you’re never more than 10 minutes away from having a little break times. But Morphine also encourages you to work longer, to build up your allowance, and then spend it more wisely by zipping around your favorite sites as quickly as possible.

Morphine is a free extension for Google Chrome.