If a dependent person suddenly stops taking amphetamines, they will have withdrawal symptoms because their body has to readjust to functioning without the drug. People may also have a long but restless sleep, often interrupted by nightmares. Dependence People who are physically dependent on amphetamines, usually develop tolerance to the drug, that is, it is necessary to take more and more to get the same effect. It is unsafe to drive after using amphetamines. They affect the ability to judge speed and distance and coordination is greatly reduced.
Amphetamines also increase confidence and drivers are more likely to take dangerous risks.