September 3, 2026

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Hi Everyone,

"Let me sleep on it" rarely works the way most of us use it. We push the decision away, go to bed, and wake up with the same options and the same doubts.

The research explains why.

Sleep can measurably improve your answer to a hard problem, but only when you do one thing first — and it's the step most people skip.

Today we're sharing the five-minute version of “sleeping on it” that works.

The step most people skip

In a study published in Nature, researchers gave people a number puzzle with a hidden shortcut. One group practiced the puzzle and then slept for eight hours. Another group practiced and stayed awake.

The people who slept were more than twice as likely to find the shortcut.

Now the detail that matters most... When people slept without practicing the puzzle first, sleep gave them no advantage at all.

During the night, your brain reorganizes what it took in during the day and connects pieces that stayed separate while you were awake. If you never worked through the problem, there's nothing to reorganize.

So the common version of sleeping on it, where you drop the decision and hope the morning brings clarity, leaves out the one ingredient the effect depends on.

Five minutes before bed

Give your brain the same starting point the puzzle group had. Before bed, write three lines about the decision:

1. The decision you're facing, in one sentence
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2. The options in front of you, including "wait"
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3. The one question you can't answer yet

Writing the note does what the practice round did for the puzzle group. It hands your brain a problem it recognizes, and the reorganizing happens on its own while you sleep.

In the morning, read the note and close it with a decision, so it doesn't turn into one more open item on your list.

You'll often catch a problem you missed the evening before, like a cost you didn't consider. If the answer looks the same in the morning, decide and move on.

Don't sleep on easy decisions

This only works on hard problems. A Lancaster University study found that a night of sleep helped people solve difficult problems and made no difference on easy ones.

Save the technique for the genuinely hard calls, where the options are close, the information is incomplete, and the choice is expensive to reverse. Everything else gets decided in the meeting.

When the answer waits until morning, tell people when they'll get it. 'I'll give you my answer at ten tomorrow' works.

Go deeper

👉 ScienceDaily: Old adage 'sleep on it' is true — but only if it's a really difficult problem — a two-minute read on the Lancaster study, handy when someone asks why you're not sleeping on everything.

👉 NIH: Quick catnaps may spark creativity — for the days you can't wait until tomorrow: even the first minute of dozing off measurably helps with hard problems.

👉 Amazon: Jeff Bezos' 2016 letter to shareholders — read the section on decision speed for the other half of this issue's rule: the calls that shouldn't wait for morning.

👉 McKinsey: Decision making in the age of urgency — use this if you suspect most of the urgency in your meetings is invented; executives themselves say most of their decision time produces nothing.

Coming up tomorrow

Tomorrow, we'll cover which of your competitive advantages AI has made easy to copy, and which ones became stronger.

P.S. Next time you say "let me sleep on it," mean the full version.