Why We Built This
We created Sleep After Coffee because we believe everyone deserves a good night's sleep. Many people don't realize how long caffeine stays in their system, leading to restless nights and groggy mornings.
Our simple calculator helps you understand exactly when caffeine will leave your body, so you can make informed decisions about your coffee consumption and sleep schedule.
How It Works
Caffeine has a half-life of approximately 5 hours in healthy adults. This means that 5 hours after consuming caffeine, half of it is still in your bloodstream.
Our calculator uses this scientifically-established half-life to show you:
- Your current estimated caffeine level
- When you'll reach 50% of your initial caffeine intake
- When you'll reach 25% (two half-lives)
- When you'll be essentially caffeine-free (under 10mg)
Did You Know?
Studies show that consuming caffeine even 6 hours before bedtime can reduce total sleep time by more than 1 hour. That afternoon coffee at 3 PM could still be affecting your sleep at 9 PM!
The Science Behind Caffeine
Caffeine works by blocking adenosine receptors in your brain. Adenosine is a neurotransmitter that promotes sleepiness, so when caffeine blocks it, you feel more alert and awake.
However, individual responses to caffeine vary based on:
- Genetics — Some people metabolize caffeine faster than others due to variations in the CYP1A2 gene
- Age — Older adults tend to process caffeine more slowly
- Pregnancy — Caffeine half-life can extend to 9-11 hours during pregnancy
- Smoking — Smokers metabolize caffeine about 50% faster
- Medications — Certain medications can affect caffeine metabolism
- Liver health — Liver conditions can significantly slow caffeine processing
Tips for Better Sleep
- Set a "caffeine curfew" — aim to stop consuming caffeine 8-10 hours before bedtime
- Be aware of hidden caffeine sources like chocolate, some medications, and decaf coffee (which still contains small amounts)
- If you're sensitive to caffeine, consider switching to tea in the afternoon, which has less caffeine than coffee
- Keep a sleep diary to understand how caffeine affects your personal sleep quality
Our Commitment
Sleep After Coffee is and always will be free to use. We believe everyone should have access to tools that help them live healthier lives.
All calculations happen directly in your browser — we don't collect or store any of your personal data. Your caffeine habits are your business, not ours.