You read the same paragraph three times and still have no idea what it says. You open your laptop to finish a report and, twenty minutes later, you are in another tab with no memory of how you got there. You walk into the kitchen and go blank in front of the fridge. You tell yourself it is tiredness and it will pass, but it has been like this for weeks.

A lack of concentration is not a diagnosis. It is a symptom, and one of the most widely shared there is: it appears on the list for anxiety, for depression, for insomnia, for ADHD and for several physical problems. That is why the useful question is not how to concentrate through sheer willpower, but what is causing it. Here we go through the most common causes, the signs that help tell them apart and which test can guide you in each case.

What is a lack of concentration, and when is it no longer normal?

Concentrating means holding your attention on one thing and keeping everything else out for as long as needed. Nobody manages it all the time. After a bad night, with a big worry on your mind or in a noisy office, anyone struggles, and that is not a sign of a problem.

It is worth looking at more closely when one of these applies:

  • It is a change. You used to read a book or get through your work without effort, and now you cannot.
  • It lasts. It is not a couple of bad days but weeks.
  • It has consequences. You make mistakes at work, fail exams, forget appointments or take twice as long to do the same things.
  • It comes with other changes. You are sleeping worse, or you are more irritable, sadder or more worried than usual.

Always, or only for a while? The key question

If you could ask yourself only one question, make it this one. When difficulty concentrating has been with you since school, with the same lapses at every stage of your life, the clue points towards ADHD. When it is recent and did not happen before, most likely something has changed: your sleep, your workload, your mood or your health. It is not a foolproof rule, because some people with ADHD compensate for years until life gets more complicated, but it brings a lot of order to the search.

Why can't I concentrate? The most common causes

Sleeping too little or badly

It is a very common cause and an easy one to overlook. The NHS lists among the effects of insomnia finding it difficult to concentrate during the day because you are tired. According to the same source, adults need 7 to 9 hours of sleep on average, and if you are tired every day, you are probably not getting enough. It is not always about sleeping too few hours: waking up many times or getting up just as tired also counts. Loud snoring or gasping and choking noises at night, together with tiredness during the day, can be a sign of sleep apnoea that is worth raising with your doctor.

The Insomnia Test looks at both your difficulty sleeping and its effects during the day. If what keeps you awake is a mind that will not switch off when you go to bed, there are specific steps in Anxiety at night: why it hits when you go to bed and how to stop it.

Ongoing stress and exhaustion

When there are more fronts open than you can deal with, your attention jumps from one to the next and settles on none of them. For a short time you can cope; when the pressure goes on for months, the built-up tiredness does the rest. The NHS lists stress among the common causes of tiredness, along with lack of sleep and difficult life events such as bereavement or looking after a new baby.

If the wear and tear is mainly about work and comes with distance or cynicism towards what you do, it may be burnout. To measure the overall load there is the Stress Test, and for work-related exhaustion, the Burnout Test. We explain the differences between the three in Stress, anxiety or burnout: how to tell what is happening to you.

Anxiety: your mind is somewhere else

With anxiety, attention is not lost: worry takes it. While you try to read, part of your mind goes over what could go wrong, and what is left for the task is not much. The World Health Organization lists trouble concentrating or making decisions among the symptoms of anxiety disorders, along with irritability, tension, restlessness and difficulty sleeping.

One clue: if your concentration comes back as soon as whatever was worrying you is resolved, then goes again with the next worry, anxiety is a strong candidate. If you also go over the same thing again and again, you may find Overthinking: why you cannot stop turning things over useful. The Anxiety Test includes the seven items of the GAD-7, a public-domain screening questionnaire, plus seven more on physical symptoms and avoidance.

Depression: when thinking takes effort

In depression, the lack of concentration comes from somewhere else. There is less noise in your head and more of an empty tank: everything is an effort, small decisions become huge, and some people describe it as a slow or foggy mind. The WHO includes poor concentration among the symptoms of a depressive episode, along with disturbed sleep, marked tiredness or low energy, and excessive guilt. What defines it is low mood or a loss of interest in things you used to enjoy, for most of the day, nearly every day, for at least two weeks.

If you recognise yourself here, the Depression Test includes the nine items of the PHQ-9. And if you are not sure whether worry or low mood weighs more, the comparison in Anxiety or depression: how to tell them apart and what to do if you have both clears it up.

ADHD in adults: when it has always been there

The NHS describes signs of inattention in adults as being easily distracted or forgetful, finding it hard to organise your time, finding it hard to follow instructions or finish tasks, and often losing things like your wallet, mobile or keys. These may or may not come with restlessness, impulsiveness or being very talkative. What sets ADHD apart from the other causes is the history: symptoms usually start before the age of 12, and the assessment specifically asks about childhood and school.

One important nuance: according to the NHS, ADHD is recognised less often in women, possibly because women with ADHD more commonly have inattentive symptoms, which are harder to spot than hyperactivity. Anxiety and depression can also make ADHD symptoms worse, so it is not unusual for them to go together. The ADHD Test has 18 questions inspired by the DSM-5 criteria and the WHO's ASRS screening scale. If what weighs on you most is putting everything off until tomorrow, also read Procrastination: why it is not laziness and what sits underneath, and for the bigger picture, Neurodivergence in adults: what it means, signs and where to start.

Physical causes worth ruling out

Not everything is psychological. The NHS points out that tiredness that lasts and has no explanation can be a sign of a medical condition such as iron deficiency anaemia, diabetes, an overactive thyroid or sleep apnoea, and that some medical treatments and medicines cause drowsiness. The hormonal changes of the menopause can bring problems with memory or concentration, and long COVID includes the same complaint, known as brain fog. So if your lack of concentration comes with other physical symptoms, the first step is your GP.

How to tell what is behind your lack of concentration

This table cannot diagnose anyone, but it helps show where the clues point and which questionnaire makes sense to try first:

If, as well as not concentrating… It may point to… What can guide you
It has happened since school, you lose things and leave tasks half done ADHD ADHD Test
Your mind keeps anticipating problems and you are tense Anxiety Anxiety Test
For more than two weeks you have had no drive or interest in almost anything Depression Depression Test
You sleep too little or badly, or wake up just as tired Insomnia Insomnia Test
You have too many fronts open and never switch off Stress Stress Test
Work has drained you and you no longer care as you used to Burnout Burnout Test
There is loud snoring, palpitations, great thirst or hormonal changes A physical cause See a doctor

Usually several rows overlap. The NHS counts stress, anxiety and depression among the most common causes of insomnia, lack of sleep makes concentration worse, and in ADHD anxiety and depression make the symptoms worse. If you score high on several questionnaires, that does not mean you have five different problems; it means it is worth having a professional look at the whole picture.

What helps you concentrate better in the meantime

No technique makes up for a cause that is still there, but some changes help almost always:

  • Protect your sleep. Regular hours and the amount you need, which for an adult is 7 to 9 hours on average. Avoid screens, caffeine and alcohol close to bedtime.
  • One thing at a time. Close the tabs you do not need and silence your phone while you work. Every interruption means starting up again.
  • Work in short blocks with real breaks in between, instead of marathons in which your attention ends up drifting off on its own.
  • Get things out of your head. Writing down what is pending on paper saves you from having to keep remembering it.
  • Move. The NHS notes that exercise helps reduce symptoms of anxiety and depression.
  • Ask for adjustments if you need them. A quiet place to work or written instructions, two of the adjustments the NHS mentions for ADHD, suit almost anyone.
Woman writing with full concentration at her desk, one way to improve concentration

If a few weeks go by and nothing changes, the problem probably is not the technique.

When to see someone

  • If it lasts for weeks and is costing you performance, at work or in your studies.
  • If it comes with sadness, constant worry or insomnia. Treating the cause usually brings concentration back along the way.
  • If it has always been there and you suspect ADHD: diagnosis in adults requires a specialist assessment that reviews your history since childhood.
  • If it comes on suddenly, with confusion, difficulty speaking or loss of strength: that is an emergency, so call 112 or your local emergency number.

If thoughts of harming yourself also appear, that is dealt with today: in Spain there is the 024 helpline, free, confidential and available 24 hours a day; elsewhere, contact your local emergency services.

Which test to take if you can't concentrate

All the MyPsicoTest questionnaires are free and anonymous, take between three and five minutes, and the result is calculated on your own device without your answers being stored or sent anywhere. For a lack of concentration, these are the most useful:

  • ADHD Test: 18 questions on inattention, hyperactivity and impulsivity over the last six months.
  • Anxiety Test: 14 questions on worry, nervousness, physical symptoms and avoidance over the last two weeks.
  • Depression Test: 12 questions on your mood over the last two weeks.
  • Insomnia Test: 12 questions on how you sleep and how it affects you during the day.
  • Stress Test and Burnout Test: perceived stress over the last month and work-related exhaustion over the last three.

Start with the one that best matches your row in the table. None of them is a diagnosis, but each gives you a concrete measure to take to an appointment and to compare later if you improve. The rest are in the psychological tests catalogue, and if you do not know where to start, Mental health test: what it measures, which ones exist and how to read your result explains how to choose.

If your result worries you or you want a professional assessment, you can talk to Xènia Capel Salcedo, a licensed psychologist (COPC reg. 14982), who offers a free first consultation call and online therapy from anywhere.

MyPsicoTest team · Updated: