First, take this with a grain of sea salt since I am no medical professional 
In short be very careful with going on any of these benzo drugs (e.g. diazepam, lorazepam), the increase ammonia level can damage your liver and cause a variety of issues outline in the Hepatic encephalopathy document. From my limited research the best way to avoid this is to use enzymes to aid protein digestion and take L-ornithine (restricted in Canada ) during high ammonia flare ups.
My Dad is affected with this issue so until I could figure this out by connecting the dots we have found that Coffee Enemas help and the usual liver support herbs. However the benzo drugs are so addictive that withdrawal can be a slow and painful episode. Worse, once the encephalopathy has started the benzo drugs themselves cause insomnia instead of sleep, most all which is outlined in the link below:Read up on Benzodiazepines (Benzo) drugs here: http://www.benzo.org.uk/FAQ1.1.htm#1
"It is more difficult to withdraw people from benzodiazepines than it is from heroin. It just seems that the dependency is so ingrained and the withdrawal symptoms you get are so intolerable that people have a great deal of problem coming off. The other aspect is that with heroin, usually the withdrawal is over within a week or so. With benzodiazepines, a proportion of patients go on to long term withdrawal and they have very unpleasant symptoms for month after month, and I get letters from people saying you can go on for two years or more. Some of the tranquilliser groups can document people who still have symptoms ten years after stopping." - Professor M H Lader, Royal Maudesley Hospital