Why a caffeine cut-off helps
Caffeine has a half-life of about 5–6 hours. That means if you have a coffee at 4pm, roughly half of that caffeine is still in your body around 10pm. It works by blocking adenosine — the natural chemical that makes you feel sleepy — so even if you manage to fall asleep, caffeine can quietly reduce your deep sleep.
Giving yourself a cut-off time lets the caffeine wear off before bed, so you fall asleep faster and sleep more deeply.
Caffeine hides in more than coffee
- Tea (black and green) contains caffeine too.
- Energy drinks and cola are common evening culprits.
- Dark chocolate and some pain relievers contain small amounts.