You Need to Protect Your PreFrontal Cortex!

Your PreFrontal Cortex (PFC) is one of your best assets.

When it comes to leading a business, a team, and indeed yourself, you need to think straight. This is especially true in today’s madness, with all its uncertainty and extreme polarities. You need the space to think things through, understand the issues well before acting, reach out to others to sense-check and get perspective, and overall have sufficient resilience to react according to your values and not your stress reaction that might be triggered because of how mad or unjust it all is!

But your PFC is under siege.

The PFC is the part of the brain that allows you to focus, solve problems, manage impulses, and take the long view. It’s the “executive” of your brain. But it’s also incredibly fragile. It fatigues easily, it’s susceptible to stress, and when it goes offline (which it often does), you’re not leading—you’re surviving.

In our coaching and consulting work with thousands of leaders in the Resilience Dynamic, we’ve found our original research is borne out in a striking pattern: those who lead with sustained impact operate using what we discovered as the ‘65/35 Rule’. That is, 65% of their time is spent engaging the PFC—doing focused, high-value work—while 35% is consciously allocated to fostering adaptive capacity: replenishing, pacing, and shifting perspective.

(To learn more read the first article in this series “Rediscovering The Ability To Focus”.)

This isn’t just nice-to-have. It’s neuroscience.

Over-Processing Leads To Poor PFC Function

When you’re constantly in meetings, figuring out what needs to change, making decisions, and responding to the needs of others, your PFC gets overloaded. When that happens, your brain defaults to your Default Node Network for processing. This is an older system within the brain which operates on the basis of fear or reward. One of its primary components is the amygdala which ensures you are alert and keeping yourself safe. It’s fantastic for reacting, but rubbish for proacting. And therefore if left to its own devices, the Default Node Network is terrible for leading.

This is why you might find yourself firefighting, short-fused, or stuck in tunnel vision, especially when you feel stressed. You are not learning, you don’t have perspective, and your performance drops to mediocre. Here, the PFC doesn’t get destroyed—but it does go quiet. And when it quiets down, so does your strategic thinking, empathy, creativity, and ability to assess risk.

So how do you keep the PFC online? By not using it 100% of the time. That’s where the ‘65/35 Rule’ comes in.

The ‘65/35′ Way: A Strategic Investment in Your Brain

The most effective leaders we coach don’t just do things differently—they think differently about time. They protect their thinking resource—literally their PFC—by structuring their days, weeks, and seasons around the ‘65/35 principle’. Here’s how it works:

• 65% Focus Time: This is your “PFC engaged” zone. Deep work. Strategic decisions. High-quality conversations. Visioning. It’s about quality, not quantity—and crucially, it’s best done in bursts, not marathons.
• 35% Adaptive Capacity Time: This is not downtime in the traditional sense. It’s deliberate space for:
  • Replenishing: physical movement, hydration, rest, and play.
  • Pacing: assessing capacity versus workload; sense-checking if all challenges ahead need attention and focus, working to optimise rhythm, with intentional transitions between tasks.
  • Perspective: stepping back to reflect, sense-checking with others, listening, ensuring you are ‘on the balcony’ (Reference Ronald Heifitz), and so can reframe priorities.

This isn’t a work-life balance mantra. It’s a brain-optimisation strategy. The 35% isn’t a reward after hard work—it’s what enables the hard work.

The Science Behind the ’65/35 Rule’

Several research-backed principles indirectly support the idea that focusing for about two-thirds of your work time while spending the remaining third on recovery activities may lead to the best outcomes.

The Pomodoro Technique and Attention Fatigue

• Studies on attentional capacity (e.g., research by John Sweller on cognitive load theory) suggest that the brain can sustain deep focus for about 25–50 minutes before cognitive fatigue sets in.
• The Pomodoro Technique, which suggests working in 25–50 minute blocks with 5–15 minute breaks, indirectly aligns with a 65% work / 35% recovery structure over a full workday.

💡 Implication: Overloading your cognitive resources leads to diminishing returns, making a structured mix of focus plus breaks more effective than continuous focus.

The Ultradian Rhythm and 90-Minute Work Cycles

• Research by Nathaniel Kleitman, a sleep researcher, found that our brains follow ultradian rhythms, natural cycles of high and low energy that last 90 minutes on average.
• The “Basic Rest-Activity Cycle” (BRAC) suggests that after 90 minutes of high focus, we need 20–30 minutes of recovery to maintain cognitive efficiency throughout the day.
• If a workday is 8 hours (480 minutes), following 90-minute cycles with breaks results in roughly 65% work and 35% recovery time.

💡 Implication: Align with your biological rhythms (i.e., ~65% work and ~35% rest) will optimise cognitive performance and prevent burnout.

The 4-Day Workweek and Reduced Hours Studies

• The four-day workweek is gaining momentum globally, underpinned by compelling scientific research, a growing list of adopters, and vocal support from influential leaders.
• Research on reduced workweeks (such as the UK Pilot Study in 2022, Iceland’s 4-day workweek trial, Spain’s experience) all have found that working fewer hours led to equal or higher productivity, with the upside of significant health benefits.
• Several prominent figures are championing the four-day workweek:​
  • 4 Day Week Global executives, Dave Whelehan and Andrew Barnes promote the “100-80-100” model—100% pay, 80% time, and 100% productivity—emphasising the benefits of reduced work hours on health and performance. Barnes has been instrumental in initiating global trials and advocating for the four-day workweek as a means to improve work-life balance and productivity.
  • A professor at the University of Cambridge, Brendan Burchell, led the UK’s largest four-day workweek trial, providing academic backing for its efficacy.
• The general takeaway is that overworking reduces efficiency, supporting the idea that optimal focus time is less than full work time.

💡 Implication: Strategic rest and recovery improve productivity; forcing more focus time does not lead to better performance.

The “Deliberate Practice” Model in Elite Performance

• Anders Ericsson’s research on deliberate practice (studying expert performers like musicians and athletes) found that:
  • Top performers work in focused blocks of 4–5 hours per day, rarely exceeding that.
  • Most effective practice schedules involve highly focused effort interspersed with rest and reflection.
• The total deliberate practice time accounts for about 60–70% of the total available time, with 30–40% dedicated to recovery, reflection, and non-cognitive activities.

💡 Implication: High performance comes from intentional, structured focus, not from maximising total hours spent working.

Recovery Boosts Cognitive Performance & Creativity

• Barbara Fredrickson’s Broaden-and-Build Theory shows that periods of recovery enhance cognitive flexibility and problem-solving.
• Sleep research (Matthew Walker, “Why We Sleep”) confirms that downtime is critical for memory consolidation and learning.
• Taking breaks has been shown to enhance creativity, decision-making, and problem-solving (e.g., research on diffuse vs. focused thinking by neuroscientists like Mihaly Csikszentmihalyi).

💡 Implication: Rest isn’t wasted time—it actively enhances problem-solving, memory, and creativity.

Practical Tips to Protect Your PFC

1. Signal Safety to Your Brain

A simple exhale, a walk in nature, or a positive connection with a colleague signals “I’m safe” to your nervous system—keeping your PFC online.

This is one of the most accessible, real and practical things you can do for your self-leadership. It is also one of the most practical things you can do to boost the collective PFC of your team – go for a walk, free-wheel together for a while on the problems you face, and see what insights pop up.

Given the right conditions for your Default Mode Network and the amygdala to quieten down, lo and behold your PFC will reignite.

2. Use Micro-Boosts

Every 90 minutes, step away for 5–10. Breathe. Walk. Look out a window. This isn’t laziness—it’s maintenance.

3. Design Focus Windows

Protect two x 90-minute blocks in your day for deep, focused work.

Turn off notifications. This is your PFC prime time—don’t waste it on swiping or email!

4. Build In Perspective Practices

This is one of the key areas for our coaching. We help teams build processes to enhance their resilience, ensuring they are creating impact, rather than being overwhelmed by busyness and not able to see what really matters.

To get going, consider reviewing priorities and impact each week.

End your day by asking: “What did I learn? What needs to change?”

End your week with your team by asking: “What did we learn? What needs reframing?”

5. Optimise Decision Making To Avoid Fatigue

Ensure your hardest decisions are made when your PFC is freshest—usually early or mid-morning.

Aim to batch similar decisions.

Automate the trivial.

Conclusion: ‘65/35’ Works!

You may feel constantly the temptation to go-go-go. But sprinting 100% of the time leads to mediocrity, confusion and procrastination. All stress induced.

If you want to lift the PFC siege, to shift from being reactive to proactive, start protecting your PreFrontal Cortex.

The ‘65/35’ way of operating leads to impact and adaptability will be fostered. So don’t accept to just do more; aim instead to think better.

Author: Jenny Campbell Founder and CEO of the Resilience Dynamic

Follow Jenny on LinkedIn for more of her thoughts, resilience research, and ideas.