Combining alcohol with any other drug (including over-the-counter or prescribed medications) can be unpleasant and dangerous. The effects of one drug may be greatly increased by the other. Consuming alcohol with other depressant drugs such as sleeping pills can be fatal, as this can cause the central nervous system to switch off brain and heart activity. Contrary to popular belief, alcohol does contribute energy or kilojoules (kJ) to the diet. Every gram (g) of alcohol contains 29kJ of energy. A standard drink contains 10g of alcohol. One glass of beer, wine, spirits or mixed drinks equals approximately one standard drink. Alcoholic cider and cans of premixed spirits equal at least one-and-a-half standard drinks.