insomnia

Don't know why, but I have had insomnia for about 6 months now. I am so tired in the evening that I can hardly keep my eyes open when Dave and I are watching TV. I feel like I am ready for bed. I go to bed and sometimes even fall asleep, but 30 minutes later, I am wide awake. I hear Dave snoring softly and get more and more irritated that I cannot fall back to sleep, especially since he is sleeping so soundly. Then I worry that I will wake him up with my moving around to get comfortable. The more I try to lie still, the more the urge to move comes over me. So I go to the couch. There I can usually kick and squirm and thrash until I finally fall asleep. Then 2 hours later, I am awake again. This goes on all night. Starts all over the next evening.