Hi friend,
I've also suffered a lot with sleep throughout this addiction, and especially during recovery periods. If this is indeed a withdrawal symptom for you (and it's highly likely that it is), in some sense, there's not much you can do except being patient and understanding that it's a symptom that will eventually pass.
Having said that, you can help the physiology of your body by sticking to some healthy routines. You can google many things that you can do to improve sleep. From my experience, having a systematic sleep/wake schedule, being physically active throughout the day (e.g. with exercise), and avoiding screens 1-2 hours before bedtime, have the most profound effect on sleep health. Also, I've recently come to appreciate that getting enough sunlight during the day (ideally soon after you wake up, for 15-20 minutes at least) has a tremendous effect on sleep initiation. This is one of the main mechanisms our bodies know when we should be wakeful and when we should get sleep, given that nowadays we can spend all day inside our homes with artificial lights, fucking up our biological clocks. Finally, caffeine, alcohol and other drugs can also have detrimental effects on sleep.
Essentially, it boils down to fixing your circadian rhythms and being physically tired enough, to help your body initiate sleep. Although I don't know about your daily routines, I would suggest you try these 3 protocols for 5 days, and see what happens.
Hope this helps.