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Sleep Cycles: Why 90 Minutes Matter

Wake between cycles, not mid-dream — bedtime math, nap science and the caffeine cut-off, calculated free.

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Sleep Cycle Calculator (When to Sleep)

Bedtimes that complete whole 90-minute cycles before your alarm — wake between cycles, not mid-dream.

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Wake-Up Time Calculator (If I Sleep Now)

Going to bed now? The alarm times that land between cycles instead of inside one.

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Nap Calculator (Power Nap Timing)

The three evidence-backed nap lengths — 20, 90, and the caffeine-nap trick — timed to your clock.

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Sleep Debt Calculator

Your week's accumulated shortfall against personal need — and the honest science of repaying it.

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Caffeine Cut-Off Calculator

Your personal last-coffee time from bedtime and metabolism speed — half-life math applied to sleep.

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Jet Lag Adjustment Calculator

Recovery days and a light-exposure plan from time zones crossed and direction — circadian science, packaged.

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