www.sleep-aid-tips.com is a very interesting site with lots of natural sleep aid tips and home remedies.
The site includes a section on instant fixes for insomnia:
If all else fails and you are still awake in the dead of night, try some or all, of these quick insomnia cures:
- Lie on your back with your knees propped up on a small pillow.
- Sleep with your head pointing in the direction North.
- Get up the same time every morning and go to bed at the same time every night for a week.
- Visualize yourself in a peaceful place, such as a field full of wildflowers with a gentle breeze blowing, or near a gently flowing stream where you can see fish swimming past you.
- Visualize a boring scenario, such as a lecture you have no interest in.
- Read out loud the names and numbers from the phone book.
- Reserve your bedroom and the bed as a place for sleep only.
- Wiggle your toes gently until you fall asleep.
- Rub your stomach lightly.
- Cut up a mild onion, place in a jar by the bed and sniff before retiring.
- Think of ten wonderful things that have happened to you today.
- Squeeze all your muscles together tightly for a few minutes and then relax.
- Threaten yourself that “If I am not asleep within the next 10 minutes, I will get up and…” clean the oven, or clean the fridge….whatever you really hate doing… When your brain knows you really mean it - this will scare you to sleep to avoid a nasty chore!

you can always try a warm cup of chamomile tea before bed if you try it around the time you start yawning it should work effectively try to avoid using sugar in it.
also if you don't want to try a sleeping aid such as tylenol pm, or advil pm you could try somthing like benadryl take 2 tablet instead of 1 or 1 and a half if that doesn't work try 3 but you really shouldn't exceed that.
if you want to avoid taking pills all together and aren't up for drinking tea you can always eliminate caffine for a day and when your in your room sit on alternative furniture or the floor use your bed as a place for sleeping only.
you can try simple things such as setting a schedule and sticking to it like they said above go to bed every night at the same time and get up around the same time you can also try building up to a full nights sleep by setting a specific time in the afternoon for a 1-2 hour nap and then try to go to bed avoid sleeping any longer so as not to confuse your body.
another simple solution could be as easy as stripping and remaking your bed completely and taking a nice warm shower before going to bed being nice and clean and crawling in to a crisp & clean bed is always relaxing.