This does not call for panic or for rejecting medication. It does call for looking more closely, weighing again and daring to adjust.

When the system is set too sharp

In some people a picture arises that fits central sensitisation. This is a description, and not a diagnosis, of a nervous system that is structurally set too high. The brain starts to pass on signals such as pain, tiredness, stimuli and stress faster and harder.

This can show itself in a combination of complaints:

• lasting restlessness and tension
• poor or shallow sleep
• muscle pain, headache, jaw clenching
• brain fog and slow thinking
• overstimulation
• emotional instability
• rapid exhaustion

These complaints are often diffuse and changeable. They do not fit neatly into a box, and that is why they are sometimes missed.

What stimulants do in the body

ADHD medication works by strengthening the activation system of the brain. That helps with attention, inhibition and staying on task. At the same time this system raises general arousal. Think of slightly higher alertness, more muscle tension and a smaller margin between action and recovery.

An important distinction:

• Non-amphetamines: methylphenidate
• Amphetamines: dexamfetamine and lisdexamfetamine

Both groups are stimulants, but amphetamines act more directly and more powerfully on dopamine and noradrenaline. In practice amphetamines give some people more physical activation, such as a higher heart rate, more tension and poorer sleep.

That does not mean these medicines are bad. It means they ask more of the stress and recovery system.

When the tipping point comes

Problems seldom arise through medication alone. The tipping point often comes through accumulation. Think of combinations such as:

• long-term use of stimulants
• chronic stress at work or at home
• trauma or insecure attachment
• perfectionism and high pressure on yourself
• lack of sleep
• hormonal changes
• physical complaints or pain
• substance use

If the body has few real moments of recovery for months or years, the system can get stuck in the ‘on’ position. A medicine that helps at first can then contribute to overload later.

Why this is often not recognised

First, the complaints resemble ADHD itself. Restlessness, concentration problems and irritability are then seen as a return of symptoms, while they can also be side effects or accumulated stress.

Second, reassessments sometimes fade into the background. Repeat prescriptions are practical, but without periodic evaluation you miss the moment when the balance tips.

Third, there is overlap with trauma, anxiety and depression. These can disturb attention and concentration just as well. If that context is not taken into account enough, someone sometimes gets a label and medication while the core lies elsewhere.

Differences between men and women

In women ADHD often shows itself in a less classic way. Inner restlessness, worrying and emotional overload are more often in the foreground. Trauma and mood complaints also play a part more often.

That increases the chance that problems with attention and concentration are treated with stimulants while the nervous system is already overloaded. In that case medication can help for a time, but in the longer term put more pressure on what someone can carry.

Methylphenidate or amphetamine: does it matter?

Yes and no. People react differently. What gives one person calm and focus makes another feel rushed. Broadly speaking:

• methylphenidate works more mildly and for a shorter time, often with somewhat less physical activation
• amphetamines work more powerfully and for longer, with more tension and sleep problems in some people

Which group someone gets depends on age, earlier experiences, side effects, duration of action and local prescribing habits. That is why groups in research are never fully comparable.

In practice: how do you stay out of the danger zone?

If you use ADHD medication, it helps to look regularly at how you are functioning as a whole.

Signs that your system is set too high:

• you sleep worse, also when you are tired
• stimuli come in harder
• your body feels tense or restless
• your heart rate feels raised
• your concentration becomes narrow and rigid
• you recover slowly after stress

What you can then do together with your prescriber:

• reassess the aim of the medication
• look at sleep and recovery as well as focus
• measure resting heart rate, tension and mood for a period
• consider a lower dose or another medicine
• take stress regulation and trauma treatment seriously
• put sleep and rhythm first

Adjusting is not failing. Neither is continuing. It is about tuning to what your system can handle now.

The middle way

ADHD medication is not an enemy, and it is not a maintenance product that you can keep using without thinking. It asks for attention, periodic recalibration and an eye for context.

If you notice that you are always ‘on’, do not think only in terms of more or less ADHD. Look also at the load on your stress and arousal system. Sometimes the key to getting back room, rest and flexibility lies there.

Jim van Os

Prof. dr. Jim van Os, Chair Division Neuroscience, Utrecht University Medical Centre. Jim works at the interface of ‘hard’ brain science, health services research, art and subjective experiences of people with ‘lived experience’ in mental healthcare. 

Jim has been appearing on the Thomson-Reuter Web of Science list of ‘most influential scientific minds of our time’ since 2014. In 2014 he published his book ‘Beyond DSM-5‘, and in 2016 the book ‘Good Mental Health Care’. In 2026 he published 'Wat psychisch lijden is'.

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Blogs by Jim van Os can be read here

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