Caffeine has a half-life of roughly five to six hours, which means a quarter of your afternoon cup is still circulating at midnight.
Practical rules
- Last cup eight hours before bed
- Delay the first cup ninety minutes after waking
- Keep the dose steady rather than escalating
Evidence
Trials that shift caffeine timing without reducing dose still improve measured sleep quality.
Same coffee, better nights.
This article is educational and not medical advice. It isn’t a diagnosis or a treatment plan — talk to a qualified clinician before changing what you take.