James was on a mission. He had a 300-mile drive ahead of him and it was already 2 PM. To stay alert and safe on the road, he grabbed a large energy drink containing exactly 200mg of caffeine. He cruised through the drive, but when he got home at 9 PM, he felt like a live wire.

A 200mg dose is standard for a "Grande" coffee or a strong energy drink. Many people assume it's out of their system by bedtime. Let's look at James's timeline:

• 2 PM: 200mg (Peak alertness)
• 7 PM (5 hours later): 100mg still active.
• Midnight (10 hours later): 50mg still active—this is like drinking a cup of coffee right as you're trying to sleep!
• 5 AM (15 hours later): 25mg active. Even while "sleeping," James's brain had to process this stimulant.
• 10 AM (20 hours later): 12.5mg active. The "ghost" of yesterday's drink is still there.

The takeaway: Total clearance takes much longer than the "buzz" lasts. If James had used our calculator, he might have chosen a smaller 50mg boost or a power nap instead.

Visualize your own decay. Don't let a 2 PM drink ruin your 11 PM sleep!