Guides

Understand the science behind the tools

Short, plain-language guides on the sleep research each calculator is built on.

How Sleep Cycles Actually Work
Light, deep, and REM sleep — what each stage does and why cycle length matters for when you wake up.
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Chronotypes: Lion, Bear, Wolf, or Dolphin?
Why some people are naturally early risers and others aren't — and what to do about it.
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Caffeine and Sleep: The Full Picture
How caffeine actually delays sleep at the chemical level, and how to time your last cup.
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The Science of Napping
What research says about nap length, timing, and who benefits most.
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