What time should I stop caffeine for the best sleep?

Caffeine has a half-life of approximately 5–7 hours in most adults (longer in those with a CYP1A2 slow metabolizer genotype), meaning a 200 mg coffee at 2 PM leaves approximately 50–100 mg of active caffeine in your system at 10 PM, enough to delay sleep onset and reduce deep sleep time, even if you fall asleep normally (Drake et al., J Clin Sleep Med, 2013).

A study by Drake et al. (2013) found that caffeine consumed 6 hours before bedtime reduced total sleep time by more than 1 hour compared to placebo, without subjects perceiving this as significantly disrupted sleep. This is the insidious part: caffeine's sleep-disrupting effects at moderate doses are more apparent in objective sleep architecture measures than in subjective perception. Men who say "caffeine doesn't affect my sleep" are often men whose deep sleep is consistently low, they have habituated to the degraded sleep and no longer notice the difference.

Honesty Scale: Solid (1). The pharmacokinetics of caffeine and its effects on sleep are thoroughly documented.

What to do: Stop caffeine by noon (12 PM) as a default rule for 7–8 AM risers. If your natural wake time is later, shift the cutoff accordingly (wake time minus 10 hours). Switch to decaffeinated coffee or herbal tea after noon. Note that pre-workout supplements often contain 150–300 mg of caffeine, afternoon gym sessions with these products frequently cause sleep disruption that men attribute to poor sleep hygiene rather than their pre-workout timing.

For the full picture, read The Sleep Hygiene Deep Dive