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<title id="title">Sleep stages are distinct categories</title>
<desc id="desc">Taxonomy of N1 transition, N2 sleep, N3 deep or slow-wave sleep and REM. A separate note explains that more N3 usually occurs earlier and more REM later; box sizes do not represent time.</desc>
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<text x="40" y="56" font-size="34" font-weight="600" fill="#1d1d1f" text-anchor="start">Sleep stages are distinct categories</text>
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<text x="40" y="132" font-size="24" font-weight="600" fill="#6e6e73" text-anchor="start">NON-REM SLEEP</text><text x="62" y="194" font-size="28" font-weight="600" fill="#054a6b" text-anchor="start">N1</text><text x="62" y="236" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">Transition from</text>
<text x="62" y="271" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">wakefulness.</text><text x="365" y="194" font-size="28" font-weight="600" fill="#054a6b" text-anchor="start">N2</text><text x="365" y="236" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">Asleep; distinct</text>
<text x="365" y="271" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">from deep sleep.</text><text x="668" y="194" font-size="28" font-weight="600" fill="#0a5c22" text-anchor="start">N3</text><text x="668" y="236" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">Deep / slow-wave</text>
<text x="668" y="271" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">sleep.</text><text x="62" y="379" font-size="28" font-weight="600" fill="#054a6b" text-anchor="start">REM</text><text x="62" y="421" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">Active brain;</text>
<text x="62" y="456" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">rapid eye movements.</text><path d="M 343 342 L 343 489" fill="none" stroke="#6e6e73" stroke-width="3"/><text x="381" y="368" font-size="29" font-weight="600" fill="#1d1d1f" text-anchor="start">Across the night</text><text x="381" y="414" font-size="26" font-weight="400" fill="#1d1d1f" text-anchor="start">Earlier: usually more N3</text><text x="381" y="460" font-size="26" font-weight="400" fill="#1d1d1f" text-anchor="start">Later: usually more REM</text><text x="40" y="540" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">Stages recur across the night, with individual variation.</text>
<text x="40" y="575" font-size="25" font-weight="400" fill="#1d1d1f" text-anchor="start">These boxes show categories, not duration or a personal sleep trace.</text>
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<text x="40" y="647" font-size="22" font-weight="400" fill="#6e6e73" text-anchor="start">Conceptual diagram • not measured data</text>
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