Some 20,000 people nationally are estimated to suffer from the disorder and teachers may mistakenly put sufferers' inattentiveness down to laziness or indifference.
The Narcolepsy Association is now planning to recruit 100 pupils aged five to 16 with narcolepsyexcessive sleepiness for a study into the quality of life of children and adolescents with the condition. Children, parents and teachers will be asked to fill out a confidential questionnaire.
The symptoms of narcolepsy, a neurological disorder, often appear in childhood or the teenage years and can have a major effect on sufferers' school and personal lives. The condition does not affect intelligence levels, but can have an impact on concentration and achievement.
Peter Saunders, chairman of UKAN, who suffers from narcolepsy, cites the case history of a 25-year-old from Tyneside who "effectively might as well not have gone to school".
"Instead of teachers paying attention to him, they effectively confined him to a seat at the back. He sat at the back for seven years, did nothing and learnt nthing. He was less trouble being asleep than being cared for."
But in other schools sufferers are able to take a short sleep when needed. Examinations have also been rescheduled to avoid their most sleepy periods.
Notes have been given to narcoleptics to cover material they were unable to take in during regular classes.
In addition to excessive daytime sleepiness, the main symptoms of narcolepsy include:
Cataplexy - loss of muscle control in response to strong emotion such as anger or laughter. This can range from dropping of the jaw, or buckling of the legs to complete collapse.
Sleep paralysis - sufferers may find themselves unable to move or speak as they are falling asleep or waking up.
Hallucinations - intense dreamlike images or sound experienced just before falling asleep or just after waking.
Sufferers may also appear to be in a trance-like state or be "running on autopilot".
Narcolepsy is a lifetime condition but the symptoms can be controlled with drugs or simple lifestyle changes by sufferers.
Mr Saunders said more able sufferers found ways to conceal or cope, such as pairing up with others or borrowing notes. But others were "effectively cut off from their education", he said.