Caffeine cutoff

What It Means

A caffeine cutoff is the time of day you stop having coffee, tea, energy drinks and other caffeine so it has time to wear off before bed. CDC's workplace safety institute, NIOSH, advises leaving 5 or more hours between your last caffeine and sleep, and more if you're sensitive to it. The American Academy of Sleep Medicine (AASM) goes further and advises no caffeine in the afternoon or evening.

How People Say It

• "No coffee after two for me, or I'm up all night."
• "Is it too late for a latte?"
• "I switched to decaf in the afternoon and I'm sleeping better."

The Breakdown

The formula. Cutoff time = bedtime minus 5 hours (CDC NIOSH), or minus 6 hours if you want the margin from the AASM-reported study. Caffeine left at bedtime = milligrams × 0.5 raised to (hours ÷ 5), using the low end of NIOSH's 5 to 6 hour half-life.

Worked example. Bedtime is 1010,000 stepsA popular daily step goal that began as the name of a 1960s Japanese pedometer; later studies find health benefits begin well below it. See more:00 pm. The milligram figures are examples.

What the result means. A half-life is the time it takes the body to clear half of what you took in, so a drink at the cutoff still leaves about half its caffeine in you at bedtime. That's why the cutoff is a minimum, and why AASM, after the study it reported found sleep cut by more than an hour even when 400 mg was taken 6 hours before bed, advises no caffeine in the afternoon or evening. NIOSH also notes the half-life is much longer in some people.

Good to Know

For daily amounts, the FDA cites 400 milligrams a day as an amount healthy adults can generally have without dangerous, negative effects, and says how much is too much depends on things like body weight, medicines and sensitivity. NIOSH's sleep tips also list chocolate and nicotine alongside caffeine as things to avoid in the hours before sleep. If you're pregnant, take medicines, or have a heart condition, ask your doctor what's right for you. A doctor is the next step if you keep a cutoff and still can't sleep most nights.

Related Terms and Categories

• Wind-down routine

  A set of calm, screen-free activities in the last part of the evening that helps you shift from being awake to falling asleep.

• Sleep hygiene

  The everyday habits and bedroom setup that make it easier to fall asleep and stay asleep, like a steady wake-up time and a quiet, cool room.

• Afternoon slump

  The dip in energy and focus many people feel in the early to mid afternoon, linked to the body's daily hormone rhythm and to what and how much was eaten at lunch.

• Evening routine

  The set of things you do each evening, in roughly the same order, between the end of the day's work and going to bed, for yourself or a whole household.

• Circadian rhythm

  The body's roughly 24-hour cycle of physical, mental and behavioral changes, such as sleepiness at night, kept in time by a clock in the brain that follows light.

• Power nap

  A short daytime nap, about 20 minutes or less, meant to lift alertness without the grogginess that can follow a longer sleep.

Wellbeing and habits