Energy Management Over Time Management
For years, I was a time management zealot. I color-coded my calendar. I time-blocked every 30-minute slot. I tracked how many hours I spent on each project with the precision of a billing lawyer. And yet, some of my most “productive” days — fully scheduled, zero gaps — produced nothing meaningful. Meanwhile, some lazy-feeling Saturdays where I coded for two casual hours yielded breakthroughs. The realization hit me during a particularly grueling sprint at Atlassian: time is a container, not a resource. Energy is the resource. A two-hour block at 6 AM when I’m rested and caffeinated is worth more than a four-hour block at 3 PM after back-to-back meetings and a carb-heavy lunch. I stopped optimizing my calendar and started optimizing my energy. Everything changed.The Time Management Trap
Time management assumes all hours are equal. They’re not. The productivity industry sells us calendars, time-trackers, and scheduling apps as if the problem is insufficient organization. But most knowledge workers I know — especially engineers — don’t have a time problem. They have an energy problem. Signs you’re in the time management trap:- Your calendar is full but your output feels thin
- You finish the day exhausted but can’t point to what you shipped
- You schedule deep work blocks but spend them staring at the screen
- You feel most creative during “unproductive” moments (walks, showers, weekends)
- You rely on caffeine and willpower instead of natural energy rhythms
Biological Prime Time: Finding Your Peak
Everyone has a window during the day when cognitive performance peaks — Sam Carpenter calls this your “Biological Prime Time.” For most people, it’s in the morning. For some, it’s late at night. The key is knowing yours.How I Found Mine
I tracked my energy and focus for two weeks using a dead-simple method: every two hours, I rated my cognitive energy on a 1-5 scale and noted what I was doing. No app needed — just a line in Apple Notes.The Energy Audit Template
Track this for 14 days, then look for patterns:| Time | Energy (1-5) | Activity | Notes |
|---|---|---|---|
| 6 AM | |||
| 8 AM | |||
| 10 AM | |||
| 12 PM | |||
| 2 PM | |||
| 4 PM | |||
| 6 PM | |||
| 8 PM |
Ultradian Rhythms and the 90-Minute Cycle
Your body operates on approximately 90-minute cycles throughout the day — a pattern called the ultradian rhythm. Within each cycle, you have about 60-90 minutes of higher alertness followed by about 20 minutes of lower alertness where your body wants to rest. Most people push through the rest phase with caffeine or sheer willpower. This works in the short term but creates an energy debt that compounds through the day. By 3 PM, you’re running on fumes.How I Use Ultradian Rhythms
My deep work blocks are structured around 90-minute cycles: Cycle 1 (5:30-7:00 AM): Peak creative work — side projects, writing, system design. Break (7:00-7:30 AM): Family breakfast, movement, completely offline. Cycle 2 (9:30-11:00 AM): Peak work work — architecture, complex PRs, mentoring on hard problems. Break (11:00-11:30 AM): Walk, stretch, snack. Cycle 3 (11:30-1:00 PM): Moderate work — code reviews, documentation, planning. Break (1:00-2:00 PM): Lunch, walk, genuine rest. After 1 PM, I don’t attempt deep work. The ultradian rhythm doesn’t stop, but the quality of each cycle diminishes as the day progresses. Afternoon cycles are for shallow work, meetings, and admin.The 90-minute cycle isn’t a rigid clock — it varies by 10-20 minutes person to person and day to day. The principle matters more than the precision: work in focused bursts, then genuinely rest. Don’t grind continuously.
Sleep: The #1 Productivity Tool
I’m going to say something that productivity culture doesn’t want to hear: sleep is more important than any technique, tool, or system in this entire site. I’ve tracked my sleep against my output for over a year using an Apple Watch. The correlation is brutal and undeniable:- 7.5+ hours of sleep: deep work quality is high, I solve problems faster, I’m patient in meetings, creative ideas flow
- 6-7 hours of sleep: functional but not sharp. I can do the work but miss the elegant solution.
- Under 6 hours: I should have stayed in bed. Everything takes twice as long, I make mistakes, and I’m irritable with the kids.
My Sleep Protocol
- Bedtime: 9:30 PM, non-negotiable on weeknights
- Wake time: 5:15 AM (that’s 7 hours 45 minutes in bed, ~7 hours of actual sleep)
- No caffeine after 1 PM — caffeine has a half-life of 5-6 hours. A 3 PM coffee is still in your system at 9 PM
- Room temperature: Cool. I keep the bedroom at 18-19°C.
- No screens after 9 PM — Kindle Paperwhite is the exception. Phone charges in another room.
- Weekend consistency — I might sleep until 6:30 on weekends, but I don’t go to bed at midnight. Consistency protects the circadian rhythm.
The Sleep ROI Calculation
Sacrificing 1 hour of sleep to get 1 extra hour of work is always a bad trade. That hour of lost sleep will cost you 2-3 hours of reduced cognitive performance the next day. The math doesn’t work. Go to bed.The Movement-Cognition Connection
When I feel stuck on a problem — really stuck, the kind where I’ve been staring at the same function for 30 minutes — the most productive thing I can do is leave my desk. This isn’t motivation-poster advice. Exercise increases blood flow to the prefrontal cortex, triggers BDNF (brain-derived neurotrophic factor) release, and improves working memory. A 20-minute walk has been shown to improve creative problem-solving by up to 60% (Oppezzo & Schwartz, Stanford, 2014).My Movement Stack
| Activity | When | Duration | Purpose |
|---|---|---|---|
| Morning walk | After kids’ school drop-off (8:30 AM) | 20-30 min | Creative thinking, problem incubation |
| Mid-morning stretch | Between ultradian cycles (11 AM) | 5-10 min | Physical reset, prevent desk posture |
| Afternoon walk | Post-lunch (1:30 PM) | 15-20 min | Combat the post-lunch dip |
| Exercise | 3x/week (evenings or lunch) | 30-45 min | Strength training, long-term health |
| Weekend outdoor time | Saturday or Sunday morning | 60+ min | Nature exposure, family time, extended thinking |
Glucose Monitoring: What I Learned from GlucosePro
In 2024, I wore a continuous glucose monitor (CGM) for three months as part of building GlucosePro. What I learned about the relationship between food and cognition was genuinely surprising.Key Insights
Post-meal glucose spikes predict focus crashes. When my blood glucose spiked above 140 mg/dL after a meal, a focus crash followed 60-90 minutes later — almost without exception. The crash wasn’t just tiredness; it was a specific feeling of mental fog where complex reasoning became difficult. Not all foods are equal. A rice-heavy lunch spiked my glucose to 160+. A protein-and-fat-focused lunch with vegetables kept me under 120. The cognitive difference in the afternoon was dramatic — not subtle, dramatic. Meal timing matters as much as content. Eating a large meal during my biological prime time (morning) was less damaging than eating the same meal at lunch, because morning glucose regulation is generally better. But the optimal strategy was keeping mornings light. Individual variation is real. Some foods that are “healthy” by general standards spiked my glucose specifically. Oatmeal, which every health blog recommends, sent me to 155. A handful of almonds with an apple kept me at 110. You can’t optimize from generic advice — you need your own data.My Nutrition Protocol (Post-CGM)
- Morning (5:30 AM): Black coffee only. Extended the overnight fast through the first deep work cycle.
- Mid-morning (9:30 AM): First food — protein-forward. Eggs, Greek yogurt with nuts, or a protein shake. Low glycemic index.
- Lunch (12:30 PM): Largest meal of the day. Protein, healthy fats, vegetables, modest carbs. No white rice on workdays.
- Afternoon snack (3:30 PM): Nuts, fruit, or dark chocolate. Small enough to avoid a glucose spike.
- Dinner (6:30 PM): Family meal, more flexible. This is the meal where I don’t optimize — it’s social, cultural, and should be enjoyed.
Caffeine Strategy
Caffeine isn’t good or bad — it’s a tool with specific use cases and side effects. Used strategically, it enhances focus. Used carelessly, it masks fatigue and disrupts sleep.My Caffeine Rules
First cup: 5:30 AM. Aligns with the start of my first deep work cycle. This is strategic caffeine — it enhances an already-good energy window. Second cup: 9:30 AM (optional). Only if I have a demanding second deep work block. Not a daily habit. Hard cutoff: 1 PM. No exceptions. Caffeine’s half-life is 5-6 hours, meaning half the caffeine from a 1 PM coffee is still circulating at 7 PM. A 3 PM coffee is actively sabotaging your 9:30 PM bedtime. No caffeine as a rescue tool. If I’m exhausted at 2 PM, the answer is a 20-minute nap or a walk, not an espresso. Caffeine on top of exhaustion creates anxious fatigue — wired but unproductive. Weekends: reduced intake. One cup max. This prevents tolerance from building too high and keeps weekday caffeine effective.Designing Your Day Around Energy
Here’s how I put it all together. Instead of starting with a calendar and filling it with tasks, I start with my energy profile and match tasks to the appropriate energy level.The Energy-First Daily Design
The Key Insight
Most people schedule meetings whenever there’s an open slot. This means meetings randomly land in your peak cognitive window — your most expensive hours given away to status updates and alignment sessions. Flip it: protect your peak hours for deep work, schedule meetings in your energy valleys. The meetings won’t suffer — most meetings don’t require your best thinking. But your deep work will dramatically improve.Recovery as Productive Time
The final mindset shift: recovery is not the opposite of productivity. It’s a component of it. When I take a 20-minute walk between deep work cycles, I’m not “wasting time.” I’m allowing my brain to consolidate what it just processed, incubate problems in the background, and restore the attentional resources needed for the next cycle. When I go to bed at 9:30 instead of grinding until midnight, I’m not “lazy.” I’m investing in tomorrow’s cognitive performance. When I take a full day off on Sunday — no side projects, no code, no productivity thinking — I’m not “falling behind.” I’m preventing the kind of chronic depletion that makes people burn out and quit everything.My Recovery Practices
- Micro-recovery (5-10 min): Stretching, stepping outside, making tea. Between ultradian cycles.
- Meso-recovery (20-30 min): Walking, short nap, breathing exercises. Once per day, usually post-lunch.
- Macro-recovery (full day): Sunday. No side projects. Family time, reading, nature, cooking. The Sabbath principle, secularized.
- Cycle recovery (3-5 days): Between 12-week cycles. No building. Just reflection and rest.
Getting Started: The Energy Audit
If you take one thing from this article, do the two-week energy audit. It costs nothing, takes 30 seconds per check-in, and will reveal your energy profile with startling clarity.Week 1-2: Track
Every two hours, rate your energy (1-5) and note what you ate, how you slept, and what you’re doing. Use Apple Notes or a spreadsheet — simplicity is the point.Week 3: Analyze
Average each time slot across the 14 days. Identify your peak window, your valley, and your second wind. Look for patterns: does poor sleep always crush the 10 AM slot? Does a protein-heavy lunch prevent the 2 PM crash?Week 4: Redesign
Move your most important work into your peak window. Move meetings into your valley. Add recovery breaks between cycles. Cut caffeine after your identified crash point.Month 2+: Iterate
Adjust based on what you learn. Try different meal timings. Experiment with morning exercise vs. afternoon exercise. Track the impact on your deep work quality. The goal isn’t to squeeze every ounce of productivity from your biology. It’s to stop fighting your body and start working with it. When you align your work with your energy, productivity stops feeling like a battle and starts feeling like a current you’re swimming with.Related reads: Deep Work When You Have Kids for protecting the time blocks your energy design creates, Health Organization for the broader health system, and GlucosePro for the glucose monitoring tool I built from these insights.