The insomnia is one of the worst symptoms. When you are in withdrawal the ONLY thing that you want is to escape those feelings, even if only for a while. The only way to do that short of a relapse is to pass out and go to sleep. Naturally, this doesn't come easy when you are in withdrawal.
In my experience, from my most recent kick with poppy tea, the insomnia starts out brutal and slowly improves. I was on my 8th day before I dosed again and the sleeping issues were still an off and on problem. In the beginning I was getting about 4 hours of sleep, and waking up early in the morning unable to fall back asleep.
By the 8th day I was usually waking up in the middle of the night and having trouble falling back asleep for like an hour. But I was getting more than 4 hours of sleep and I would usually pass back out after I woke up, even if it took an hour or so. You are nearly over the worst of the insomnia, just wait it out a few more days. Your sleep cycle returns it just takes some time.