Mentis- Bedtime minus eight hours = your last cup. Bed at 11pm means no caffeine after 3pm.
- Caffeine six hours before bed cut sleep by more than an hour in one study.
- Count all of it: chai, coffee, cola, green tea, energy drinks, chocolate.
- In Mentis: "My Caffeine Cutoff", the keystone of chapter 4 of the Sleep plan.
How do you set a caffeine cut-off?
- Write down every cup, today. The 9am coffee, the 11am office chai, the 4pm chai with biscuits, the cola at dinner. In the app this is "Every Cup, Today".
- Count back eight hours from when you want to be asleep. That's your cut-off.
- Move, don't drop. Shift the late cups earlier, or swap them for decaf, a herbal tea, haldi doodh or water.
- Find the hidden ones: cola, green tea, dark chocolate, pre-workout drinks, some cold and pain tablets.
- Hold it for two weeks and notice how quickly you fall asleep.
Why does afternoon caffeine affect sleep?
Caffeine blocks adenosine, the chemical that builds up while you're awake and makes you sleepy. It lasts a long time: for most adults, half of it is still in the body about five hours later. So a 4pm chai is still partly active at 9pm, and some of it at midnight.
In a controlled study, people took caffeine at bedtime, three hours before, or six hours before. Even at six hours, they lost more than an hour of sleep, measured at home, and most didn't feel the difference (Drake et al., 2013). A 2023 meta-analysis found caffeine reduced total sleep by about 45 minutes and cut deep sleep, and recommended stopping coffee about 8.8 hours before bed (Gardiner et al., 2023).
When should you use it?
If you take a long time to fall asleep, sleep lightly, or rely on several cups to get through the day. It works best together with a fixed wake time and morning light, which reduce how much caffeine you need in the first place.
Where is it in the Mentis app?
Chapter 4 of the Sleep plan is called "Nothing borrowed": chai, coffee and drinks aren't running my nights. It includes the lessons "You Won't Feel It, Which Is The Problem", "The 3 PM Chai Is Still In You At 11" and "The Cup Nobody Counts", the step "Count Back Eight Hours, Find The Hidden Ones", and the audio "The 4 PM Slump".
Frequently asked questions
How long does caffeine stay in your body?
Caffeine's half-life is roughly five hours for most adults, and longer for some people. That means half of a 4pm coffee can still be in your system at 9pm.
Does chai have caffeine?
Yes. A cup of tea has less than a cup of filter coffee, but several cups add up, especially strong cutting chai. Green tea, cola, dark chocolate and some pain relievers have caffeine too.
I fall asleep fine after coffee. Is it still a problem?
Possibly. In the study, people who had caffeine six hours before bed lost over an hour of sleep but didn't rate their sleep much worse. Caffeine also reduces deep sleep, so you can fall asleep and still sleep worse.
What about the afternoon slump?
The Sleep plan's audio 'The 4 PM Slump' and the step 'Ten Minutes Out Before The Chai' are alternatives: a short walk in daylight, water, or a decaf chai.