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Caffeine cutoff time by bedtime

The only controlled trial on timing found that 400 mg of caffeine six hours before bed still cut sleep by more than an hour. Pick your bedtime for the six-hour line, the residual curve and last-cup times for 12 drinks.

Updated October 3, 2026 · Drake 2013 · FDA · IOM 2001

Bed at9:00 pmlast coffee 3:00 pmBed at9:30 pmlast coffee 3:30 pmBed at10:00 pmlast coffee 4:00 pmBed at10:30 pmlast coffee 4:30 pmBed at11:00 pmlast coffee 5:00 pmBed at11:30 pmlast coffee 5:30 pmBed at12:00 amlast coffee 6:00 pmBed at12:30 amlast coffee 6:30 pmBed at1:00 amlast coffee 7:00 pm

Why six hours

Caffeine's half-life averages about five hours (the FDA cites four to six). A 96 mg cup at the six-hour mark leaves about 42 mg at lights out; at three hours it leaves 63 mg. The trial measured sleep objectively and found the six-hour dose still cost over an hour — while participants reported no difference. Caffeine by drink →

Sources

  1. Caffeine content for coffee, tea, soda and more — Mayo Clinic
  2. Spilling the Beans: How Much Caffeine is Too Much? — U.S. Food and Drug Administration
  3. FoodData Central — U.S. Department of Agriculture
  4. Caffeine Effects on Sleep Taken 0, 3, or 6 Hours before Going to Bed — J Clin Sleep Med 9(11):1195-1200, 2013 (Drake C. et al.)
  5. Caffeine for the Sustainment of Mental Task Performance: Formulations for Military Operations — National Academies Press, 2001

General information from population studies (NIH, CDC, NSF, AASM). It is not medical advice and does not replace a clinician who knows you.