Insomnia hits me pretty bad, and quite often. It's been like a lifelong companion of mine! As for suddenly becoming more awake when you try tog o to sleep, do you have a tendency to think a lot when you're in bed? If so, you may be triggering an unconscious response to become mentally active when you try going to sleep. I've certainly been there... and what generally works for me is to just meditate to calm yourself down and more importantly, to make yourself less mentally active. You can also try three general guidelines to help with insomnia in general:
1) Don't go to bed until you're tired. Obviously, if you're tired you're less likely to lie in bed awake. Also, doing so can build a bad (subconscious) habit of not going to sleep when you go to bed, instead triggering other responses in your body (like the aforementioned).
2) Reduce exposure to mentally or physically stimulating activity at least a couple of hours before going to bed. Also, try not to eat anything soon before going to bed, and try to limit your exposure to cooler colors (such as blue, white (due to being full-spectrum), etc.). Note: If you take in a large amount of food, you can actually make yourself drowsy, but there are a few reasons why you shouldn't take in a large meal just before bed. Depending on your eating habits, taking in a large meal in general can also have undesirable consequences.
3) Do things during the day to make sure you'll be tired at night. The easiest way to accomplish this is just to knock out a couple miles at some point during the day. If you're going to do cardio for the purpose of sleeping better at night, keep in mind that you want to go quickly enough that it doesn't take an inordinate amount of time to exhaust yourself, but not so fast that you find yourself getting winded long before actual exhaustion can begin to set in. The exception is HIIT, which will make you tired in both the long run and immediately after exercising, but it can be quite hard to do if you're not used to it. Also, if you find yourself getting up late, then expect to sleep late as well. Most people have a 2:1 waking:sleeping ratio, so if you wake up at 12PM, don't expect to feel sleepy until about 16 hours later, or until about 4AM. Depending on your circadian rhythm, this may or may not be a significant issue though.
Long post is long, but hopefully at least some of this information will be helpful to you >_>.