Anyone has Sleep problem when using Mesalazine

I have been diagnosed with colitis. The doctor didn’t tell me which kind of colitis is. But they only detect inflammation after biopsy. So I guess that my disease is not Crohn's disease or ulcerative colitis. Anyway, my G.I. prescribes at first salofalk (3 tablet per day). After about two months using it, I began to have trouble sleeping. At first, I’m not sure if this is because of the drug. But later on, my family doctor have me stop using the drug for two weeks, in order to take calprotectin test. One week after I stop taking the drug, I have a flare up, but on the other hand, the sleep problems go away. After I did the test, I resumed using the drug, and sleep problem comes back one week later.
Two weeks ago, my G.I. put me on high dose of mezavant(four tablets daily) because I still have a 2 to 4 bowl movement everything days. He changed the brand and hope this could solve the sleep problem. It works well and reduce the bowl movement to once or twice a day. But it makes sleep problem even worse. Previously, I can rely on melatonin to fall into sleep. But now I have to use over-the-counter sleep aid. I will meet my G.I. in 20 days and may ask him to change the drug again. I don’t know how many alternative I have in this case.
I’m wondering if anyone have similar experience with Mesalazine. Some article says that 3% of the patient using the drug experience trouble sleeping. I do not see many people complain about that online. Especially, I’m wondering if anyone has experience of dealing such sleep problem. Thanks