Sleeping pills are drugs which are used world-wide to combat sleep disturbances, and to prevent symptoms due to maladjustment to shiftwork or jet-lag. Today, benzodiazepines and the so-called "non-benzodiazepines", such as zolpidem, which both act on benzodiazepine receptors, are drugs of first choice and they are substitutes for barbiturates. Their use as sleeping pills in insomniacs is established after appropriate medical diagnosis. Symptoms from shiftwork or jet-lag are due to an internal desynchronisation of biological rhythms, and there is ample evidence that benzodiazepines are not effective in preventing these symptoms. Cabin crews in particular should never take sleeping pills, in order not to impair cognitive functions or to reduce the reactivity needed to fly an aircraft safely. The biological clock(s) cannot be reset instantaneously by any drug.