ADHD and Caffeine: Does Coffee Help or Make You Tired?

Short answer: Caffeine is a stimulant that can make you feel more alert and energetic,¹ but it isn’t a recommended treatment for ADHD. In the Australian ADHD Guideline’s recommendations, caffeine appears only as a non-prescribed stimulant that can cause restlessness and over-activity, something clinicians should look for because it could mimic or worsen ADHD symptoms.² Feeling tired after coffee isn’t a sign of ADHD. Short sleep, caffeine wearing off and withdrawal in regular coffee drinkers are more ordinary explanations.³¹⁴

Does caffeine help ADHD?

If coffee seems to sharpen you up, that fits with what caffeine does. It stimulates your brain and nervous system, and a small amount (100–200 mg) can make you feel more alert and active.¹

Feeling more alert isn’t the same as treating ADHD, though. For adults, the Australian ADHD Guideline’s recommendations include medicine, cognitive-behavioural interventions, coaching and guidance on lifestyle factors such as diet and physical activity, and caffeine isn’t among them.² In the guideline’s recommendations, caffeine comes up in only one place: when assessing someone, clinicians are asked to look for things that could look like ADHD symptoms or make them worse, including “non-prescribed stimulants like caffeine”.²

There’s also a practical limit. Higher intakes bring side effects of their own: regular heavy use, more than 600 mg a day, can cause insomnia and anxiety.¹ Sleep problems are already common with ADHD, with studies reporting insomnia in 43–80% of adults with ADHD.⁵

If you rely on coffee to get through the day, mention it to your GP. It may be a sign that your concentration, your sleep or both need attention. For more on how ADHD affects the brain, see the ADHD brain, and for treatments other than medicine, see how to manage ADHD without medication.

Does caffeine make people with ADHD sleepy?

You may have seen claims online that coffee makes people with ADHD sleepy, or that if coffee makes you sleepy, you must have ADHD. That isn’t how ADHD is diagnosed. A diagnosis depends on a long-standing pattern of inattentive and/or hyperactive–impulsive symptoms that began in childhood,⁶ assessed against set diagnostic criteria.⁷ How you react to coffee isn’t one of those criteria.

Why does coffee make me tired?

There are several everyday reasons coffee can leave you feeling flat.

You’re short on sleep

Most adults need about 7 to 9 hours of sleep a night to feel refreshed and function at their best.³ Caffeine can lift you for a while, but when it wears off, the tiredness from a short night is still there.

The effect wears off

Caffeine’s effects usually start after about 30 minutes and can last up to 6 hours, depending on the person.¹ When they fade, you may notice tiredness that was there all along.

Withdrawal in regular coffee drinkers

Caffeine is addictive and many regular coffee drinkers become dependent on it, so cutting down quickly or stopping can cause withdrawal symptoms such as tiredness, headache, irritability and trouble concentrating.⁴ These usually start within a day of stopping.¹

Everyone responds differently

How caffeine affects you depends on your age, weight, general health, genetics and mood, and on whether you have caffeine regularly.¹ That’s one reason the same coffee can leave one person buzzing while another barely notices it.

Caffeine is disturbing your sleep

Caffeine can change your sleep patterns, especially if you have it too close to bedtime.⁴ An afternoon coffee can mean a worse night, a more tired tomorrow and another coffee to compensate.

If you’re tired most of the time no matter what you do, see your GP. Tiredness has many possible causes, and it’s worth checking properly.

Caffeine, sleep and anxiety

healthdirect advises avoiding tea, coffee and caffeinated soft drinks for at least 3 to 7 hours before going to bed.³ If you have insomnia, its advice is to limit caffeine to mornings only.⁸

That matters more if you have ADHD, because sleep difficulties are common.⁹ For more ideas, see ADHD and sleep.

Anxiety is worth thinking about too. Many people with ADHD also have anxiety or depression,⁶ and caffeine can increase feelings of anxiety.⁴ If you often feel on edge, notice whether it’s worse on days when you have more caffeine. If you decide to cut back, do it gradually to avoid withdrawal symptoms. See ADHD and anxiety.

Caffeine and ADHD medicines

Caffeine and stimulant ADHD medicines are both stimulants, and some of their effects overlap:

• The most common side effects of stimulant medicines include increased anxiety and irritability, insomnia and headache.¹⁰ Many ADHD medicines can also affect the heart, and stimulants can cause high blood pressure.¹⁰
• Even a small amount of caffeine can make your heart and breathing faster,¹ and caffeine can increase anxiety.⁴

So for some people, the two together may mean more anxiety, a faster heart rate or worse sleep. Caffeine can also interact with some medicines, including some used to treat mental illness,⁴ so ask your pharmacist or doctor whether any medicine you take could be affected by caffeine.¹

Tell your doctor roughly how much caffeine you have, including energy drinks. The Australian ADHD Guideline recommends monitoring heart rate, blood pressure, sleep and anxiety when medicine doses are adjusted,² and your caffeine intake is part of that picture. If you think caffeine and your medicine aren’t mixing well, talk to your doctor rather than changing how you take your medicine.

What about energy drinks?

A 250 mL can of energy drink contains about 80 mg of caffeine.¹ In Australia, energy drinks can contain no more than 320 mg of caffeine per litre and must be labelled as not suitable for young children, pregnant or lactating women, and people sensitive to caffeine.¹¹

Be careful mixing energy drinks with alcohol: the caffeine can hide some of the effects of the alcohol.¹ See ADHD and alcohol.

Practical tips

• Know your total. Count coffee, tea, cola and energy drinks. Some pain-relief and cough medicines also contain small amounts of caffeine.¹
• Stay within healthy limits. healthdirect says healthy adults can safely have around 400 mg a day, about 2 espressos or 4 instant coffees, and that it’s a good idea to have less if you have a medical condition.¹
• Set a cut-off time. Stop at least 3 to 7 hours before bed,³ or keep caffeine to the morning if you have insomnia.⁸
• Cut down gradually. Reducing quickly or stopping suddenly can bring on withdrawal symptoms, so if you want to cut back, do it slowly.⁴
• Try swaps. Replacing some of your usual drinks with decaf, herbal tea or water lowers your total without giving up the ritual of a hot drink or a break.
• Don’t use caffeine to cover a sleep problem. If you’re tired despite a reasonable bedtime, talk to your GP.
• Be open with your doctor about how much caffeine you have, especially if you take ADHD medicine.

Frequently asked questions

Does caffeine help ADHD?

Caffeine is a stimulant and can make you feel more alert, but it isn’t a recommended treatment for ADHD. In the Australian ADHD Guideline’s recommendations, caffeine appears only as something that can cause restlessness and over-activity, which clinicians should look for when assessing symptoms.

Why does coffee make me tired?

Common reasons include not getting enough sleep, caffeine wearing off after a few hours, and withdrawal in regular coffee drinkers, which can cause tiredness and poor concentration. Caffeine late in the day can also disturb your sleep and leave you more tired the next day.

Is it a sign of ADHD if caffeine makes you sleepy?

No. ADHD is diagnosed from a long-standing pattern of symptoms that began in childhood and affect daily life, not from how you react to coffee. If you’re tired all the time, it’s worth talking to your GP.

Can you drink coffee while taking ADHD medication?

Ask your doctor or pharmacist. Stimulant ADHD medicines and caffeine can both affect your heart and both can contribute to anxiety and sleep problems, so together they may add to side effects for some people.

Are energy drinks bad for ADHD?

They’re not a treatment for ADHD, and they can contain a lot of caffeine: about 80 mg in a 250 mL can. They must be labelled as not suitable for people sensitive to caffeine, and mixing them with alcohol can hide some of alcohol’s effects.

How much caffeine is safe for adults?

healthdirect says healthy adults can safely have around 400 mg of caffeine a day, about 4 instant coffees or 2 espressos. It’s a good idea to have less if you have a medical condition, and to check with your pharmacist or doctor whether caffeine affects any medicine you take.

Next steps

Read ADHD medication in Australia and adult ADHD myths, or start with the free ADHD self-assessment.

This article is general information only and is not medical advice. Only a qualified health professional can diagnose ADHD. ADHD GP is a private telehealth clinic staffed by AHPRA-registered Australian GPs.

Book your ADHD assessment

References

1. healthdirect (Australian Government). Caffeine. 2025. www.healthdirect.gov.au — Caffeine stimulates the brain; effects start in about 30 minutes and last up to 6 hours; healthy adults can safely have about 400 mg a day; a 250 mL energy drink has about 80 mg; caffeine can mask alcohol’s effects.
2. Australian ADHD Professionals Association. Australian ADHD Guideline — summary of recommendations. 2022. adhdguideline.aadpa.com.au — Medication is the most effective treatment for core symptoms, with non-medication treatments adding support (3.1.1); diagnosing clinicians should be registered and trained in ADHD assessment (2.1.1); the diagnosis must be confirmed before starting medication (5.1.2); CBT should be offered to adults (4.2.11); stimulants are first-line for impairing adult ADHD, with heart rate, blood pressure, weight, sleep, mood and anxiety monitored during titration; co-occurring conditions get best-practice treatment.
3. healthdirect (Australian Government). Sleep. 2023. www.healthdirect.gov.au — Most adults need about 7 to 9 hours of sleep; avoid alcohol for at least 4 hours before bed, and tea, coffee and caffeinated soft drinks for at least 3 to 7 hours before bed.
4. healthdirect (Australian Government). Food, drink and mental health. 2024. www.healthdirect.gov.au — Caffeine can increase anxiety and change sleep patterns, and regular users can get withdrawal symptoms such as tiredness; alcohol is a depressant that often worsens sleep in the second half of the night.
5. Wynchank D, Bijlenga D, Beekman AT, Kooij JJS, Penninx BW. Adult Attention-Deficit/Hyperactivity Disorder (ADHD) and Insomnia: an Update of the Literature. Current Psychiatry Reports. 2017. PubMed PMID 29086065 — Studies report insomnia in 43–80% of adults with ADHD.
6. healthdirect (Australian Government). Attention deficit hyperactivity disorder (ADHD). 2025. www.healthdirect.gov.au — ADHD is a neurodevelopmental condition that begins in early childhood; around 1 in 20 people in Australia has ADHD; it is partly genetic; an adult diagnosis requires evidence that symptoms began in childhood; learning difficulties can occur alongside it.
7. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 2013. www.psychiatry.org — Diagnostic criteria for ADHD, including the five-symptom threshold for adults aged 17 and over.
8. healthdirect (Australian Government). Insomnia. 2025. www.healthdirect.gov.au — To help with insomnia: cut out nicotine, reduce or cut out alcohol, and limit caffeine to mornings only.
9. Better Health Channel (Victorian Government). ADHD — adults. 2026. www.betterhealth.vic.gov.au — About 7 in 10 children continue to experience ADHD symptoms as adults; treatment can include education, psychological support, coaching, practical strategies and medication.
10. healthdirect (Australian Government). ADHD medicines — children and adults. 2025. www.healthdirect.gov.au — Stimulants adjust dopamine and noradrenaline; short-acting forms work soon after a dose and long-acting forms last longer; common side effects include reduced appetite, weight loss, anxiety, irritability and insomnia, and stimulants can raise blood pressure; prescribing is tightly controlled and there is a risk of dependence if not taken as prescribed.
11. Food Standards Australia New Zealand. Caffeine. 2025. www.foodstandards.gov.au — Energy drinks may contain no more than 320 mg of caffeine per litre and must be labelled as not suitable for young children, pregnant or lactating women and people sensitive to caffeine.

Sources were last checked on 5 October 2026. See all sources used on this site on our Sources page.