Alcohol acts as a depressant on the central nervous system - dulling the senses and increasing mental and physical reaction times. Even a small amount of alcohol leads to a decline in an individual’s performance and may cause his judgment (i.e. ability to gauge his performance) to be hindered. Alcohol may remain circulating in the blood for a considerable time, especially if taken with food. Aircraft maintenance engineers must anticipate this effect upon their next duty period. It is especially important to note that combinations of alcohol and sleeping tablets, or anti-histamines, can form a highly dangerous and even lethal combination. Never drink alcohol when you are on medication!