Caffeine cutoff

1. Set your bedtime. Your cutoff is six hours before it.
2. Add each coffee, tea, energy drink or soda when you have it. Change the amount to match the label if you can.
3. The chart shows roughly how much is still in your body through the evening, and the line marks your bedtime.

It's a rough estimate. We use a simple model where caffeine halves every few hours, and real bodies vary.

In a sleep study, people took 400 mg of caffeine at bedtime, 3 hours before, or 6 hours before. All three disturbed their sleep compared with a dummy pill. The researchers backed the advice to stop caffeine at least 6 hours before bed (Drake et al., 2013 (opens in a new tab)).

Caffeine leaves slowly. Half of it is usually gone in 4 to 6 hours, but in adults that can be anywhere from 1.5 to 10 hours (Guest et al., 2021 (opens in a new tab)). So an energy drink at dinner can still be with you at midnight.

For healthy adults, the FDA (opens in a new tab) cites 400 mg a day as an amount not generally linked to harmful effects, and says people vary widely in how sensitive they are. A 16 oz energy drink can have anywhere from 54 to 328 mg.

• Before a late session, when you're deciding whether to open another can.
• On days you can't fall asleep and want to see why.

Medical experts advise against energy drinks for children and teens (FDA (opens in a new tab)). If you're pregnant, trying to be, or breastfeeding, ask your doctor or midwife how much caffeine is OK for you.