I have a close friend who got a card for medical marijuana. He said it was a get-high-for-free card. His deal was that he had a caregiver, and that every six weeks he received two ounces of his choice of medical weed strains for free. After two years, he was smoking it all up, and then having to purchase extra grams until his next delivery day. He decided to quit. He said that the withdrawal was bad. He said that after two days, he couldn't get to sleep, and when he did, he would wake up thinking it's morning, but it was actually only an hour that had gone by. He said it got worse as the days went by. After four days he said he would just watch the clock as the hours passed. He also reported slipping into sleep and then waking up feeling hot and then start sweating. He had to change the sheets in the middle of the night. And then he lost weight and found it almost impossible to keep food down. This scared the shit out of him. I'm sure you weren't a heavy smoker like my friend, but maybe you smoked just enough to where abstinence upset your sleep. Just a thought.
It'll always be a little hard to sleep working night hours. I've been working first shift for the first time in 10 years and after 2 weeks of fighting insomnia get to sleep easy and wake up well rested. Good luck. I find clearing your mind and thinking about things you did as a youth to help you sleep knocks me out. Laying down and thinking of past mistakes or humanities flaws will keep you tossing and turning for hours