Until last year, women in the US had been unwittingly overdosing on sleeping pills for nearly twenty years.

In January 2013, the American Food and Drug Administration (FDA) ordered drug companies to slash the dosing of Zolpidem (an insomnia drug known as Ambien) by half for women. Side-effects from over-dosing on Zolpidem (known as Stilnox in Australia) include impaired thinking and reaction time, sleep-driving and sleep-eating.

The FDA ordered the makers of Ambien to provide different dosing instructions for males and females. Prior to their decision, the instructions for men and women were exactly the same. Why? Because we still don’t have enough information about how men and women metabolise drugs differently.