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Frequently Asked Questions (Perimenopause Cortisol & Caffeine Half-Life Sleep Calculator)
Does caffeine metabolism slow down in perimenopause and after 40?
Yes—hormonal shifts and estrogen fluctuations slow CYP1A2 liver enzyme clearance, extending caffeine's half-life from 4.5 hours to 6–7+ hours.
Why wait 60–90 minutes after waking for your first cup of coffee?
Letting your natural morning cortisol awakening response peak and clear residual adenosine prevents the 2:00 PM energy crash.
Can I still fall asleep with 40mg of caffeine in my system?
You may fall asleep, but wearable and EEG studies show residual caffeine reduces restorative Stage 3 deep slow-wave sleep by 15%–25%.
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