Blue light has become the bogeyman of evening screen use, and the picture in the literature is messier than the marketing suggests. We walk the actual melatonin-suppression evidence, the melanopsin and ipRGC mechanism, why intensity and timing matter far more than the color filter on your phone, what Night Shift and warm front-lights genuinely do, and a calibrated take on screens before sleep.
Sleep
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Blue Light and Circadian Rhythm -
Caffeine Pharmacokinetics for Engineers How caffeine actually works inside your body: adenosine receptor antagonism, the 5-hour half-life math that explains why your 3 PM cup is still measurable at midnight, tolerance and withdrawal as receptor upregulation, CYP1A2 genetic variation, and dose-response curves for alertness versus anxiety — written for people who reason in graphs and decay equations.
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Sleep Architecture and On-Call: The Engineer's Body on Rotating Shifts How NREM and REM sleep are organized across the night, why a 4 AM page hurts more than a 4 AM party, what sleep debt actually costs, and how to design on-call rotations and personal countermeasures that respect the biology instead of fighting it.