Clever pills

A more recent finding is that in addition to increasing wakefulness, modafinil appears to improve performance. Scientists at Cambridge University trialed it on healthy volunteers, who scored higher on computer games designed to test their mental function, compared with volunteers given a 'dummy' pill.

They also showed less impulsive responses and a greater tendency to think carefully about the tasks they were given. Experts say it could help people to remember things and make them better at problem solving.

Who is using it without prescription?
It is estimated that 90 per cent of Modafinil use is 'off-license'. In the US, it is increasingly used by college students, long-distance lorry drivers, shift workers whose sleep pattern isn't bad enough to fall into the 'moderate to severe' medical use category, computer programmers, and others wanting to solve their 'over-commitment' problems.

The drug is also popular with clubbers and some athletes have tested positive for it. It is known that the US military use it, and the UK military have also taken a great interest, having reportedly stockpiled thousands of pills in the run-up to the Iraq war.

What is the down side?
Other arousal drugs that affect the dopamine system tend to be addictive, so there are some worries that there is a chance that Modafinil will also cause dependency with long-term use. The manufacturers have acknowledged the potential for dependence with long-term use in their data sheet for patients.

Some doctors are concerned that such problems will only become apparent after the drug has been in use for a longer period of time. It is possible that users may have to keep increasing their dose to get the same effect.

What are the side effects?
The most common side effect is headache, which has been reported in more than 10 per cent of users. Between one per cent and 10 per cent of users suffer other side effects such as abdominal pain, extreme fatigue, chest pain, palpitations, flushing, nausea or diarrhoea. Mental symptoms include irritability, nervousness, insomnia, anxiety, depression, and confusion. The list of uncommon side effects is huge and rather scary, but only rarely reported.

Women who could become pregnant must use a very reliable method of contraception while using Modafinil, and for two months after last using it. Modafinil can make all hormonal contraceptives less effective, which poses a problem for women wanting to use it.

What are the risks of sleep deprivation?
Sleep deprivation is known to weaken the immune system and increase susceptibility to serious infection. Sleep is necessary to maintain good health. Sleep deprivation affects blood pressure, heart rate, and the production of insulin and other hormones, so any measures that encourage long periods without sleep can affect the body in ways which are not apparent to the user and which may not be compensated for in short periods of 'catch-up' sleep.

What are the implications of widespread social use?
Widespread social use would pose many social and ethical questions. Do we want a society in which drug use allows us to be much more workaholic and our society to become even more obsessed with productivity and achievement?

If student populations use it widely to improve performance or to stay awake long enough to make a deadline, will they feel they have to continue using it to maintain their 'normal' marks.

In a society with competitive performance markers, is it ethical to allow people to use them to gain advantage over non-users? Will parents who discourage their children from using performance-enhancing drugs be putting them at a disadvantage? It is certainly food for thought.