Ativan (lorazepam) is a short acting benzodiazepine used for anxiety, sedation, and sleep. It also has muscle relaxant properties. You want something for "rest" so I assume you are primarily looking for a medication for insomnia. If so, several non-benzodiazepine varieties are available, like Ambien, Sonata and Rozerem. Speak to your physician about them, or visit their respective websites for more information.
If muscle spasm is still a concern, then you may need to add a prescription muscle relaxer also. Options include Flexeril (cyclobenzaprine), baclofen, Skelaxin, Zanaflex and others.
Of course, most importantly, you need to talk with your physician and discuss your needs. Keeping a journal of your sleep experiences and any other related issues is a good idea. Best wishes. Hope this helps.