HAVIT Blog
Science-backed guides on habits, sleep, nutrition, and movement.
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Business Travel Hotel Room Workout Protocol: 20-Minute Routines That Actually Work
You can maintain 94% of your strength gains with just three 20-minute bodyweight sessions per week while traveling—no gym required.
Your Caffeine Cutoff Time Isn't 2PM: How CYP1A2 Genetics Determine When to Stop
Your genes determine whether caffeine's half-life is 2 hours or 12 hours—making the generic 2PM cutoff advice potentially useless or overly restrictive for you.
Your Caffeine Cutoff Time Is Probably Wrong: How to Calculate It Based on Your Genetics
Your genes determine if caffeine stays in your system 3 hours or 9 hours—calculate your true cutoff time using the CYP1A2-based formula below.
Caffeine Half-Life by Age and Genetics: Your Personal Cutoff Time Calculator
Caffeine half-life ranges from 2 to 12 hours based on your CYP1A2 genotype and age, making generic 2pm cutoff advice potentially wrong for your body.
How to Find Your Personal Caffeine Metabolism Rate Using Sleep and HRV Data
Your caffeine half-life is probably somewhere between 2 and 12 hours—track sleep latency and HRV patterns for 14 days to find your personal cutoff time without expensive genetic testing.
Caffeine Half-Life and Sleep: How to Calculate Your Personal Cutoff Time
Your caffeine cutoff time depends on your personal half-life (3-9 hours)—most people should stop 8-10 hours before bed, but genetics can shift this by hours.
Your Caffeine Cutoff Time Is Probably Wrong: How to Track What Actually Works for Your Sleep
Your caffeine half-life ranges from 3-9 hours based on genetics—tracking your actual response beats following generic advice.
Caffeine and Metabolism: Why Your Morning Coffee Stopped Working (And How to Fix It)
Caffeine increases metabolic rate by 3-11%, but tolerance develops within 1-4 weeks; strategic cycling protocols can preserve these benefits indefinitely.
Caffeine, Fat Burning, and the Tolerance Trap: Why Your Coffee Stops Working
Caffeine boosts fat oxidation by 10-29%, but tolerance develops within 1-2 weeks of daily use—strategic cycling restores its metabolic effects.
Caffeine Metabolism and Weight Loss: Finding Your Optimal Timing and Dose in 2026
Caffeine can boost metabolism by 3-11% and fat oxidation by up to 29%, but timing it 30-45 minutes before activity and matching dose to your CYP1A2 gene status maximizes results.
Your Caffeine Cutoff Time Is Written in Your DNA: The CYP1A2 Gene Guide
Your CYP1A2 gene variant determines if caffeine clears in 2 hours or lingers for 10—knowing your type reveals your true cutoff time for protected sleep.
Why You Sleep Like a Rock While Camping (And How to Sleep Even Better)
Camping exposure to natural light can reset your circadian rhythm in just 2-4 days—here's how to maximize that effect while staying comfortable outdoors.
