This disorder is usually acquired in one of four ways: One cause is benzodiazepine drugs such as; midazolam, flunitrazepam, lorazepam, temazepam, nitrazepam, triazolam, clonazepam, alprazolam, diazepam, and nimetazepam; all of which are known to have powerful amnesic effects. This has also been recorded in non-benzodiazapine sedatives or "z-drugs" which act on the same set of receptors; such as zolpidem (also known as Ambien), eszopiclone (also known as Lunesta), and zopiclone (also known by brand names Imovane and Zimovane).[3] A second cause is a traumatic brain injury in which damage is usually done to the hippocampus or surrounding cortices. It may also be caused by a shocking event or an emotional disorder.[4]