Relapsing during sleepless nights

This has been a big problem for me as well. Insomnia, not just from long lasting urges but as a withdrawal symptom it self has broken me down too many times, and honestly the best advice I can give isn't really all that great. First I'd say to try making yourself tired while distracting your mind. Laying in bed feeling miserable won't help. Its actually better to get up and do something mentally distracting but low key, like cleaning, and after a bit lay down again.

Truthfully, this has only helped some of the time, and if it doesn't, the only other thing that's worked is to go through it instead of around it; To not give in no matter what and if that means not sleeping, so be it. Obviously you won't feel too great the next day, but it's just one day and I can guarantee you'll fall asleep the next night. I know I'm not giving you a magic bullet here that does the trick everytime, but when withdrawal hits and it messes with sleep its generally not fun to deal with.

Somethings that might be preventative might be to exercise and tire yourself out before the evening or taking melatonin before bed. Both have helped me fall asleep easier, but neither is a guarantee.