Caffeine is the world's most consumed substance, and it's clear why. Caffeine gives a boost of energy that gets people ready for the rest of the day. However, while that morning coffee or midday energy drink may give you an instant boost, it could be quietly messing with your sleep schedule causing poor sleep and a growing dependence for caffeine.
According to the American Academy of Sleep Medicine, the mean half-life of caffeine in an average person is 5 hours. This is the metric that we used for our tool.
Caffeine Estimates:
• Brewed coffee (8 oz): ~95 mg
• Espresso (1 shot, 1 oz): ~63 mg
• Black tea (8 oz): ~47 mg
• Green tea (8 oz): ~28 mg
• Energy drink (8 oz): ~80 mg
• Soda (12 oz): ~30–40 mg
How Long Does Caffeine Last in Your System?
Caffeine does not leave your system quickly. According to the American Academy of Sleep Medicine, its half-life is 5 hours — meaning after 5 hours half of the caffeine still remains in your system. So if you consume a cup of coffee with 160 mg of caffeine at 4:00 p.m., you can still have 80 mg of it lingering at 9:00 p.m. This is a quiet and often unforeseen consequence of a large caffeine intake. Even when you no longer have the jitters, caffeine can still have an effect on your body. This can result in trouble falling asleep or getting deep, restful sleep.
Why Timing Matters
Sleep experts recommend cutting off caffeine intake at least six hours before bedtime. For most people, that means no caffeine after around 4:00 p.m. But if you’re especially sensitive to caffeine, even earlier cutoffs — or cutting it out altogether — might be necessary to protect your sleep quality. There is no good substitute for good sleep, but caffeine can deter that from even being an option. The caffeine left in your body when you go to sleep, can prevent deep sleeping making it harder to feel refreshed. This in turn continues the cycle making you depend on caffeine throughout the day.
A Smarter Way to Use Caffeine
Caffeine is a wonderful tool — but, as with any tool, it's best to use with discretion. Our Caffeine Half-Life Calculator will help you get an estimate of how much caffeine might still be in your system and for how long. It's a simple way to better time your strategy and protect your sleep. If you're struggling with low energy levels, lack of focus, and sleepless nights, try these non-caffeine methods to become more alert:
• Stay hydrated
• Sleep 7–9 hours per night
• Eat more plant-based foods
• Exercise daily
• Cut back on napping
Your energy — and your sleep — are worth more than a cup of coffee.