If you have only been smoking Weed for 5 years then the insomnia from quitting it shouldn't last that long. However, that can still mean trouble sleeping up to 6 months. I have a lot of experience with Pot and even more experience with quitting Pot. The 1st time I quit Pot I had been smoking it about 15 years but not every night. I had been smoking it every night for about 7 years, and the severe insomnia lasted about 6 months. However, I didn't sleep normally again until about 1 year. After about 1.5 years I started to sleep more than usual, and I think my brain was trying to catch up on lost sleep. By 2 years I was fine. But then after 3 years I made 1 of the dumbest decisions of my life. I went back to smoking Pot. I didn't intend to keep smoking it, but I just couldn't stop again. I didn't stop for another 20 years, and that was only because I lost everything I had to buy weed. So I had to quit. This is why the last thing you should do is start again. You may not be able to stop again. I'm now clean 8 years and I love being clean. I love not smoking weed anymore. So don't start again. And right now you can just stop taking Lorazepam. You haven't been taking it so long that stopping abruptly is an issue. And then do what the previous poster said. Use the various OTC drugs to help sleep. Almost every one of the OTC meds has the same active ingredient in it. I forget what it's called, but it's the same drug that Benadryl is. It starts with a D. Learn to read the active ingredients. I think the one exception is Unisom. There should be 2 forms of Unisom. One has the same active ingredient as all the rest do, but 1 has something different. So what it boils down to is there are 3 OTC sleeping drugs. There's the original Unisom. Then there's the drug in Benadryl, and then there is Melatonin. Don't disregard Melatonin without trying it. Melatonin can work very good. The problem with Melatonin is some people become immune to it very quickly. If that happens then switch to something else for a while, and then after a while you can use Melatonin again.
Then there are the herbs that promote sleep. Some of these work best when combined, and that's what Sleepytime tea is. Individually the herbs are Valerian root and Chamomile, plus a few others who's names I forget. I have found it helpful to add 1 or 2 bags of Chamomile to 2 bags of Sleepytime tea. Usually you have to make the tea stronger than they say on the package, especially if you've been used to taking a drug like Benadryl. Benadryl is a powerful drug, so don't take too much. You'll sleep way over 12 hours and wake up with a hangover. So go easy on it.
But quit the Lorazepam because your grandmother probably needs them, and they are addictive. And do yourself a favor and quit the weed. I smoked weed a total of 35 years and according to my doc I'll never sleep normal again. Pot can do serious harm to you, even though it takes a long time to do it. But once it's done, there's no coming back from it. Pot is not the harmless drug everyone thinks it is.
Just do what I'm telling you, and you'll be fine someday.