#sleep
4 articles
One 90 mg Coffee Needs 2.5 to 6.8 Hours Before Bed to Drop Under 50 mg. Your Half-Life Decides Which
Caffeine's half-life ranges from 1.5 to 9.5 hours between healthy adults, per the Institute of Medicine. We ran one filter coffee and a double through the half-life math at 3, 4, 5, 6 and 8 hours to see how far back your cutoff really needs to be.
6 Hours/Night Costs Kevin $14,500/Year (and 1-2 Years of Lifespan)
Kevin's $95K salary at 6 hours of sleep: ~12% productivity loss + $1,800 healthcare + 2-3 extra sick days = ~$14K/year cash cost. Plus a measurable lifespan reduction the dollar framing can't capture.
4+ Hours of Daily Recreational Screen Time Is the US Average — And Blue Light Alone Delays Sleep by ~30 Minutes
Nielsen puts the average adult at 4+ hours a day. Harvard Health's research on blue light and melatonin explains why that number quietly eats into sleep quality on top of the hours themselves.
Waking Up Mid-Cycle Feels Worse Than Sleeping Less — the AASM's 90-Minute Cycle Explains Why
Sleep science consensus puts a full cycle at roughly 90 minutes: light, deep, REM. Timing wake-up to land at a cycle boundary, rather than mid-deep-sleep, changes how rested you feel independent of total hours.