When to take caffeine (and when to stop)

01How fast it kicks in

Caffeine is absorbed quickly. Blood levels usually peak within about 30 to 60 minutes of eating or drinking it. That is why many people take caffeine half an hour before they need to be sharp: before a meeting, a workout or the second half of a drive.

02How long it lasts

Your body clears caffeine slowly. Its half-life in healthy adults is roughly 3 to 7 hours, often quoted as about 5. So if you take 100 mg at 4 pm, around 50 mg may still be in your system at 9 pm.

03Protect your sleep

In a well-known study published in the Journal of Clinical Sleep Medicine (Drake et al., 2013), 400 mg of caffeine taken even six hours before bed cut total sleep by more than an hour. Participants often did not notice the difference themselves.

If you sleep at 11 pm, make 5 pm your last call. Earlier is better if you are sensitive.

04A simple daily plan

1. Wake up: drink water first. Many people find waiting 60 to 90 minutes before the first coffee feels smoother, though evidence for a fixed delay is mixed.
2. Mid-morning: your first caffeine, if you want it.
3. After lunch (1 to 3 pm): the natural afternoon dip. A small dose here, plus a short walk, works for many. See beating the afternoon slump.
4. Before a workout: 30 to 60 minutes ahead.
5. Six hours before bed: caffeine off.

05Why small doses help

A small amount of caffeine taken when you need it often works better than one big dose in the morning. That is the logic behind pocket formats like a candy: you can take a little at the moment the dip hits, instead of a large drink that lingers into the evening.

Fin.