Benzodiazepines possess anterograde amnesic properties, disrupting both short-term and long-term memory function. The amount of amnesia is systematically related to dose effects and half-life differences among the benzodiazepines. Memory deficits are found for episodic, semantic, and iconic memory function. The deficits in long-term memory are probably the result of a disruption of consolidation of information in memory and not retrieval from memory. The disruption is produced by rapid sleep onset. Thus the long-term amnesia is really a retrograde effect of sleep and not the anterograde effect of the drug.