You wake from a nightmare in the middle of the night. You are in a state of abject terror: your heart is pounding, and your skin prickles with sweat.
This is the same feeling of terror some children experience every day at school. Walking down the corridor is a heart-racing trial, reading aloud a test of stamina, assembly a succession of horrors.
But pupils who suffer anxiety often go unnoticed, according to Samantha Cartwright-Hatton, a clinical psychologist at Manchester University. Anxiety can be difficult to spot - even for trained psychologists. For many teachers coping with classroom pressures, the symptoms are indistinguishable from general behavioural difficulties.
Dr Cartwright-Hatton will be presenting workshops around the country this month, based on her research with anxious pupils.
"If an anxious child is threatened by something in the environment, they can really kick out," she said. "By being naughty, they are trying to get out of the situation."
Other children express their anxiety by withdrawing into themselves. They become shy, refuse to speak or find it difficult to make friends. Some cling to their parents, or cry regularly.
Most anxious children are distressed by change, so a new teacher or new approach to lessons can be terrifying. And many fear crowds, so noisy lunch and assembly halls can be disturbingly intimidating.
The trigger for such angst is not always obvious. Psychologists believe that certain children are genetically predisposed to anxiety. "Genetics provide fertile ground," said Dr Cartwright-Hatton, "but something needs to come along and sow seeds."
These triggers can be single events, such as war or displacement. But milder trauma can also trigger anxiety: parents who are inconsistent or refuse to make time for their children, for example. And children can imitate parents' fears.
Because it can be so difficult to identify anxious pupils, Dr Cartwright-Hatton recommends that teachers attempt to minimise potential anxiety-inducing situations. Well-managed schools can provide a stable counterpoint to a volatile home life.
"Anxious children really need a consistent environment," she said. "Those who have done well tend to be at schools where everybody knows what the rules are. The teacher knows, the caretaker knows, the dinner lady knows."
She also recommends teachers offer regular praise for confident behaviour. So if children attempt something outside their comfort zone, however insignificant, they should be rewarded for the effort.
And teachers should be careful not to let their own anxieties show. "Anxious children are like sponges for threat information," she says. "If someone's talking about something scary, they will hear it at a thousand paces. You have to be extra super careful about conveying information that the world is dangerous and something bad will happen."
For more about Dr Cartwright-Hatton's Children and Anxiety workshops, tel 08444 775774