Caffeine Crash: Why It Happens and How to Avoid It

A caffeine crash is the drop in energy, focus and mood you can feel a few hours after coffee or an energy drink, as caffeine wears off and the tiredness it was holding back returns. Caffeine works mainly by blocking adenosine receptors in the brain, and the average adult clears half of it in about 5 hours (StatPearls). The most common reasons for a crash are short sleep, a large dose, caffeine late in the day that cuts into the next night's sleep, and mild withdrawal in regular coffee drinkers (Drake and colleagues, 2013; Juliano and Griffiths, 2004). This guide covers what a caffeine crash feels like, why it happens, how long it lasts, and how to avoid it.

It is educational, not medical advice.

Key Takeaways

• Why it happens: caffeine blocks adenosine, a signal of sleepiness; as it is cleared, with a half-life of about 5 hours, the tiredness comes back (StatPearls).
• Late caffeine backfires: 400 mg of caffeine taken even 6 hours before bed disrupted sleep in a home study (Drake and colleagues, 2013), which sets up tomorrow's slump.
• Regular drinkers feel withdrawal: skipping your usual caffeine can bring headache, fatigue, drowsiness and poor concentration, starting 12 to 24 hours later (Juliano and Griffiths, 2004).
• Keep it moderate: for most healthy adults, the FDA cites 400 mg a day as an amount not generally linked to negative effects (FDA).

What Is a Caffeine Crash?

A caffeine crash is not a medical diagnosis. It is the everyday name for feeling suddenly tired, flat or foggy after a caffeine boost fades. Caffeine keeps you alert mainly by blocking adenosine receptors in the brain (StatPearls). Adenosine is one of the signals that tells your brain you have been awake for a while. When caffeine is cleared from your body, that signal can reach the brain again, and if you were short on sleep to begin with, the tiredness can feel sudden.

Caffeine Crash Symptoms: What Does It Feel Like?

People describe a caffeine crash as:

• Sudden tiredness or sleepiness
• Low energy and trouble concentrating
• Irritability or a low mood
• A headache, especially if you drink caffeine every day

These overlap with the symptoms researchers have confirmed for caffeine withdrawal: headache, fatigue, low energy, decreased alertness, drowsiness, difficulty concentrating, irritability and feeling foggy (Juliano and Griffiths, 2004). Too much caffeine has its own signs, including jitters, anxiety, a fast heart rate, an upset stomach and trouble sleeping (FDA).

Why Does Caffeine Make Me Tired?

• The boost wears off: with a half-life of about 5 hours in the average adult (StatPearls), much of a morning coffee is gone by mid-afternoon.
• You were already short on sleep: caffeine can hide tiredness for a while, but it does not replace sleep. Adults need 7 or more hours a night (CDC).
• Late caffeine hurt last night's sleep: in a home study, 400 mg of caffeine at bedtime, 3 hours before or 6 hours before bed all disrupted sleep compared with placebo (Drake and colleagues, 2013).
• Mild withdrawal: regular drinkers can get symptoms when they skip or delay their usual amount, even at doses as low as 100 mg a day (Juliano and Griffiths, 2004).
• Sugar in the drink: sweet coffee drinks and energy drinks add sugar on top of the caffeine. Our guide to blood sugar spikes explains how sugary drinks affect blood sugar after you have them.
• People differ: there is wide variation in how sensitive people are to caffeine and how fast they clear it (FDA).

For the full timeline of absorption, peak and half-life, see our guide to how long caffeine lasts.

To check your daily total against the amounts experts cite, see how much caffeine is too much.

How Long Does a Caffeine Crash Last?

A typical afternoon slump eases with food, water, movement or a short rest, and usually improves after a good night's sleep. Withdrawal lasts longer: symptoms usually start 12 to 24 hours after your last caffeine, peak at 20 to 51 hours and can last 2 to 9 days (Juliano and Griffiths, 2004).

If you are weighing a measured tablet against a cup, see caffeine pills vs coffee.

How to Avoid a Caffeine Crash: 7 Tips

1. Keep your total moderate

For most healthy adults, the FDA cites 400 mg a day as an amount not generally associated with negative effects (FDA).

2. Set a caffeine cut-off

Researchers recommend avoiding substantial caffeine for at least 6 hours before bed (Drake and colleagues, 2013). If you sleep at 11 PM, that means your last coffee by about 5 PM, and earlier is better.

3. Protect your sleep

The most reliable way to need less caffeine is to sleep 7 or more hours (CDC). Our guides to how to wake up when you are tired and how much deep sleep you need can help. If short nights have been piling up, see sleep debt and how to recover from it.

4. Eat with your coffee

Have caffeine with a meal that includes protein rather than on an empty stomach, and skip the sugary syrups and energy drinks. If sweet drinks are a habit, see how to stop sugar cravings.

5. Spread it out

Several smaller servings earlier in the day are gentler than one very large one. Tea has less caffeine than most coffee, and our guide to theobromine vs caffeine covers a milder option. Our Mushroom Cacao is one cocoa based choice, with theobromine and a little natural caffeine.

6. Drink water

Keep water nearby through the day, especially if coffee is your main drink. Our guide to electrolytes covers the foods that help you stay topped up.

7. Cut back gradually

If you want to drink less caffeine, the FDA advises doing it gradually (FDA), and tapering instead of stopping suddenly can avoid withdrawal (StatPearls).

If you are cutting back, our guide to coffee alternatives compares drinks with less or no caffeine, and how to stay awake covers what helps when you are short on sleep.

How to Get Over a Caffeine Crash Right Now

Drink a glass of water, eat something with protein, and step outside or take a short walk. If you can, a short nap of around 20 minutes earlier in the afternoon is better than more caffeine late in the day; our guide to non-sleep deep rest is an option when you cannot nap. Avoid reaching for another large coffee in the late afternoon, since that can set up a worse night and a bigger crash tomorrow (Drake and colleagues, 2013).

For the best nap length and how a coffee nap works, see our guide to how long a nap should be.

L-Theanine and Caffeine: What Research Shows

L-theanine is an amino acid found in tea, which naturally contains both L-theanine and caffeine. In a trial of 27 healthy adults, 50 mg of caffeine with 100 mg of L-theanine improved speed and accuracy on an attention-switching task at 60 minutes and reduced distraction during a memory task, compared with placebo (Owen and colleagues, 2008). L-theanine does not cancel caffeine, so the same limits and cut-off still apply. Our guide to L-theanine and caffeine covers ratios and timing, and our L-theanine ingredient page explains the science.

Our Theanine Nasal Spray provides 36 mg of L-theanine per two-spray serving and contains no caffeine, so you can pair it with your coffee or tea. If you want energy support without relying on more caffeine, the Energy Stack combines NAD+ Nasal Spray, Forage and Methyl B-12 Nasal Spray in one daily routine. For more options, see supplements for energy without the crash and our non-stimulant energy and focus hub.

Pairing caffeine with creatine before workouts? See creatine and caffeine for what studies found about taking them together. For how coffee and NAD+ fit together and when to take each, see our guide to taking NAD+ with coffee. Citicoline is a non-stimulant some people take alongside coffee; our guide to citicoline vs caffeine compares the two for focus.

When to See a Doctor

Get medical help right away for chest pain, a very fast or irregular heartbeat, fainting or severe anxiety after caffeine. See a doctor if you feel exhausted most days even with enough sleep and moderate caffeine; our guide to fatigue vs burnout covers common causes to check. Talk to your doctor about caffeine if you are pregnant or breastfeeding, take medication, or have a heart condition.

Frequently Asked Questions

What is a caffeine crash?

The drop in energy, focus and mood you can feel as caffeine wears off and the tiredness it was blocking returns (StatPearls).

What are the symptoms of a caffeine crash?

Tiredness, low energy, trouble concentrating, irritability and sometimes a headache, which overlap with the confirmed symptoms of caffeine withdrawal (Juliano and Griffiths, 2004).

How long does a caffeine crash last?

An afternoon slump usually eases within hours with food, water and rest. Withdrawal after stopping regular caffeine can last 2 to 9 days (Juliano and Griffiths, 2004).

Why does coffee make me tired?

Caffeine blocks adenosine for a while; as it is cleared, with a half-life of about 5 hours, the tiredness returns, especially if you were short on sleep (StatPearls).

How do I avoid a caffeine crash?

Keep your total moderate, stop caffeine at least 6 hours before bed, sleep 7 or more hours, and have caffeine with food rather than with sugar (FDA; Drake and colleagues, 2013; CDC).

How late can I have caffeine?

Researchers recommend avoiding substantial caffeine for at least 6 hours before bedtime (Drake and colleagues, 2013).

How much caffeine is too much?

For most healthy adults, the FDA cites 400 mg a day as an amount not generally linked to negative effects; sensitivity varies widely (FDA).

Does L-theanine stop a caffeine crash?

It does not cancel caffeine. In one trial, caffeine with L-theanine improved attention more than placebo (Owen and colleagues, 2008), but moderate caffeine and good sleep matter most.

Sources

• Evans J, Richards JR, Battisti AS. Caffeine. StatPearls. Updated 2024. StatPearls
• Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013. PubMed 24235903
• Juliano LM, Griffiths RR. A critical review of caffeine withdrawal: empirical validation of symptoms and signs, incidence, severity, and associated features. Psychopharmacology (Berl). 2004. PubMed 15448977
• Owen GN, Parnell H, De Bruin EA, Rycroft JA. The combined effects of L-theanine and caffeine on cognitive performance and mood. Nutr Neurosci. 2008. PubMed 18681988
• U.S. Food and Drug Administration. Spilling the Beans: How Much Caffeine Is Too Much? FDA
• Centers for Disease Control and Prevention. About Sleep. CDC

These statements have not been evaluated by the Food and Drug Administration. This content is for education and is not medical advice. Our products are not intended to diagnose, treat, cure or prevent any disease. Talk with a healthcare provider before starting a new supplement if you are pregnant, breastfeeding or taking medication.