Any advice on Melatonin for rapid eye movement (REM) sleep?

Hi, i am a Mayo Clinic patient. I travel from my country to Mayo Clinic once a year . I will have the polysonnogram test next week. Probably my problem is from my autoinmune condition together with my complete hysterectomy and some medications I use for inflammation. After the oxymeter they told me theres level apnea and will be test for rem sleep. After my diagnosis we will discuss options as rem sleep melatonine. Ive tríed over the years with commom melatonine and have to discontinue it bc of vivid dreams that repeat every night and that stop after i stop taking the melatonine. I would like to know people with the same side effect while on melatonine and how they overcome that situation without having to stop using melatonine. Melatonine seem to be the best option for cyrcadiam rithm & want to give it a try. Is there any option about how to take the melatonine in order to avoid this terrible side effect (vivid dreams). Thanks for your suggestions and advice