Those who cannot face the day without a shot of caffeine-fuelled tea or coffee to jumpstart their brains might be woken up to an alternative stimulant, a tablet showing promise as a brain enhancer.

Cambridge University researchers believe that a prescription drug used to treat people with narcolepsy, the disorder that causes people to suffer recurrent episodes of involuntary sleep, could have wider uses.

Tests on 60 healthy young men, some on the medication known as modafinil, others on a dummy alternative, suggest the drug can bring significant improvements in mental functioning, planning complex problems, recalling strings of numbers and remembering abstract patterns.

The experiments, using touch-sensitive computer screens and easy-to-understand computer games, have led the researchers in the university's department of psychiatry to plan further tests. These will see whether young people suffering from attention deficit hyperactive disorder show the same benefits, so that it might become an alternative to ritalin.

Barbara Sahakian, who with a PhD student is conducting the work funded by the medical research council and the Wellcome Trust, believes others could benefit, such as older people recovering from brain injury. There could be advantages for military personnel, jet-lagged travellers and those who need a pick-me-up before work.

But the British National Formulary warns that modafinil, marketed as Provigil, should be used with caution, because "dependence with long-term use cannot be excluded".