The length of your break should vary depending on the volume and intensity of your work session. But as a general rule, try to break for one-third of the time you work deeply for.

WHY IT MATTERS: Proper rest is key for maintaining focus and efficiency when doing cognitively demanding work. Understanding your optimal break duration helps maximize your outputs and energy levels — ensuring you get done what you set out to do.

WHAT MOST PEOPLE GET WRONG: People don’t fully recharge because their breaks are often too short or too long. They also:

• Don't set a timer for their breaks, which invites distraction (and further increases break duration).
• Assume they need the same amount of rest regardless of how long they work for.
• Blindly follow the Pomodoro method without customizing it.

THE BENEFITS: Overcome these problems by optimizing your break times and you'll:

• Ensure your work sessions don’t drag on longer than you intended.
• Learn to customize break durations based on work volume and intensity.
• Apply flexible strategies that suit your personal work style.

HOW TO DO IT: The Pomodoro technique is the most popular method for incorporating timed breaks into multiple ‘cycles’ of focused work.

It's a good entry point for those new to focused work, but I find it lacks flexibility. I like to work longer than 25 minutes, and the 5-minute break doesn’t leave me feeling recovered.

• In my own system (which I call DeepCycles), I typically work for 30 minutes and break for 10. I'll then repeat this cycle 4-6 times (for a total of 2-3 hours of deep work).

• This amounts to breaking for one-third of the time I work for, and is a general rule I try to follow. When I work longer, say for 45-minute cycles, I'll incorporate a 15-minute break. I rarely work longer than 45 minutes straight without taking a break, as I can feel myself fatigue and become gradually less useful.

• If someone were to work for 90 minutes straight, I'd argue my one-third rule should still apply and a 30-minute break would be well-deserved.

• In fact, the longer you focus, the more rest you need. This seems surprising. You might assume the mind and body need a fixed amount of time to recharge, regardless of how long you focus for.

• But similar to strength training, volume and intensity matter. The stronger you are and the heavier the weight you lift, the more rest you need not only between sets but between training sessions.

THINGS TO CONSIDER:

• Work volume: How many cycles you work for impacts how much rest you need. If you're doing just two 45-minute cycles, you may not need to break for 15 minutes in between.
  
  But if doing a monster session of six 45-minute cycles (which I only recommend for experienced deep workers), you'll want to ensure you're breaking for the full 15 minutes.

• Work intensity: Cognitively demanding work requires higher intensity and thus more rest. If you were instead doing two 30-minute cycles of something more shallow like processing email, a five-minute break may suffice.

• Mood and energy levels: I try not to let my current mood dictate my commitment to work. I often don't feel like doing the cognitively demanding work that I scheduled for myself the night before.
  
  But once I complete a couple cycles and build momentum, I'm almost always more energized and positive than when I started out. The remaining session goes well and I’m glad I didn’t skip it because of a sour mood.
  
  So you shouldn’t normally choose your break duration depending on your energy and mood — but sometimes you do want to consider this. Maybe you're sick. Or stressed about something important. You might do better with a longer break (or fewer cycles) than you originally planned. And that's ok. Be kind to yourself above all.

THE BOTTOM LINE: Use the one-third rule as a general guideline for taking smart breaks, but customize your sessions based on work volume and intensity (while considering your mood and energy levels as needed).