Plan by Energy, Not by the Hour

The short answer: stop asking when, start asking what state

Hour-based planning treats your body as a flat-line resource that produces the same output at 10am and 3pm. It doesn't. Forty years of chronobiology research, summarised most popularly in Daniel Pink's When (source), says most people run a daily pattern of peak → trough → recovery — analytic work goes well in the peak, dies in the trough, comes back differently shaped in the recovery. If your time-blocked schedule keeps crashing, it's not that you lack discipline; you slotted a peak task into a trough hour and the body said no.

What the chronobiology actually says

Most adults — and chronotype research from Till Roenneberg has confirmed this across hundreds of thousands of people — run a circadian arc with one strong peak in the morning, a sharp trough in the early afternoon (the classic post-lunch dip, but it's not the lunch — it's the rhythm), and a softer recovery in the late afternoon and evening. Night owls run the arc shifted later by two to four hours. Within that day-long arc are shorter ultradian cycles of roughly 90 minutes, identified by Nathaniel Kleitman in the 1960s — you cycle through alertness and dullness several times within the working day, not just once.

The practical consequence is that the same hour on the clock can hand you very different attention, depending on where you are in your peak/trough arc and where you are in the current ultradian cycle. A schedule that ignores both is making decisions for a person who doesn't exist.

Five moves to plan by energy

• Map your real energy curve for a week. For seven days, write down at 10am, 1pm, 4pm and 8pm one word for your state — sharp, fine, dull, gone. After a week the pattern is visible. Peak hours are not where you wish they were; they are where the data says they are.

• Match task type to energy type. Peak hours are for analytic, decision-heavy, novel work. Trough hours are for admin, mechanical, low-stakes tasks (the data is consistent across studies — accuracy stays decent in the trough, but novel reasoning collapses). Recovery hours, counter-intuitively, are best for creative and brainstorming work — the slight cognitive looseness helps lateral thinking.

• Protect the peak ruthlessly. If your peak is 9-11am and you let it fill with email, status meetings and small decisions, you have spent your most expensive cognitive hour on cheap work. Most calendars do this. Move every recurring meeting out of the peak; if you can't, optimise the ones that touch it.

• Surrender to the trough. The post-lunch dip cannot be coffee'd away reliably. The clean win is to not schedule the day's hardest task into it. Use it for the work you'd otherwise resent doing — bills, scheduling, slack messages, expense reports. The trough is a feature, not a bug.

• Honour the 90-minute cycles inside the day. Even inside the peak, attention waxes and wanes on ~90-minute cycles. Three deep blocks separated by real (not laptop-staring) breaks beat one heroic four-hour block, every time. The technique isn't about working less; it's about respecting the rhythm so the work that happens is good.

Why this pays double for ADHD

ADHD brains have steeper energy swings than average and a less consistent baseline. Medication windows, sleep debt, food, and stimulation level all move the arc around more than they do for neurotypical readers. Treating yourself as a flat resource means almost every day breaks the plan. Planning by energy assumes you'll vary, and builds the plan around the variation instead of in spite of it.

Practically: hyperfocus windows for ADHD readers behave like extreme peaks — work that would normally take all day fits in two hours. Don't waste a hyperfocus window on routine tasks because you happened to be "on schedule" to do those. The right move is to drop the routine and ride the window; the routine work can be done in the trough. Energy-based planning is permission to do this without guilt.

Where it fails (and the repair)

• Pretending a meeting-heavy job has flexibility it doesn't. Sometimes the peak is owned by other people. The fix is to identify the one or two hours per week you do control and make those the deep-work fortress, instead of mourning the rest. A protected weekly two-hour block beats a wished-for daily one.

• Confusing tiredness with the trough. If every hour feels like a trough, the issue isn't the rhythm — it's sleep, food, or unmanaged stress. Energy planning assumes a roughly normal baseline. If the baseline is broken, fix the baseline first; the planning is downstream.

• Over-engineering the calendar. The whole point is to make planning lighter, not heavier. Two rules — peak hour is sacred, trough hour is admin — covers most of the benefit. Resist the urge to colour-code your way into a new system that itself becomes the chore.

FAQ

What if I'm a night owl?

The arc still runs — it's just shifted later by two to four hours. Your peak might be 4pm-7pm and your trough 9am-11am, the exact opposite of the early-bird stereotype. Apply the same logic: deep work in your peak, admin in your trough. Roenneberg's chronotype research strongly supports that fighting your chronotype, not just your habits, is the harder battle.

Can I shift my peak with sleep changes?

A little. Consistent sleep timing moves the arc somewhat, especially if you've been drifting. But the genetic component of chronotype is large, and most people don't fundamentally change their type from morning to evening by lifestyle alone. Better to design the work around your real type than the type you wish you had.

Does this conflict with time-blocking?

It refines it. Time-blocking is about reserving slots; energy planning is about deciding what kind of work goes in which slot. The two play well together — block the slot, choose the task by what state you'll be in then. The conflict is only with time-blocking that pretends an arbitrary 2pm hour is identical to an arbitrary 10am hour.

What about caffeine — can it just override the trough?

Reduce the trough, not erase it. Caffeine helps a little, especially if timed right after the trough starts (the so-called 'caffeine nap' tactic). But betting on caffeine to deliver a peak in your trough is reliably how the afternoon goes badly. Use it as a soft assist, not a load-bearing pillar.

How do I track my energy without it becoming another chore?

One word, four times a day, for a week. That's the whole instrument. After the pattern is visible the tracking stops — you're not building a longitudinal study, you're discovering your shape. Re-run it once or twice a year if life changes.