I've had intermittent insomnia almost my entire life - apparently even since I was a baby, according to my parents. Right now I am on medication unrelated to sleep problems, but it naturally helps regulate my sleep patterns and often makes me drowsy and tired when I need to be.
In the past I have tried many different things, and found a few things that seem to help. One is the natural sleep aid melatonin. It occurs naturally in your brain and is released in the dark to help trigger your body into sleep mode, and you can buy natural supplements of this chemical at any health store and most pharmacies. It has no adverse affects the way addictive sleeping pills often do, and it does not knock you out into a dreamless, restless state the way sleeping pills do. You take it 20-30 minutes before you are going to bed, and then when you lie down in the dark it just gives you body a slight boost of melatonin and it usually provides a longer, more restful sleep. It has worked for me often in the past and I try to take it whenever I can.
Another method I've used, although not great for your body, is to simply stay up one night when you are unable to sleep. Pull an all nighter, and when dawn comes just go about your day as normal. You will be extremely tired by the end of the day, but your overly fatigued body should basically crash by the next night and it will slightly reset your internal clock. This is not always successful in the long term if you have insomnia though, as it will work until you are fully rested, and then you will find yourself unable to sleep again.
The only other thing that has seemed to work for me, is to completely force my body to adjust to a exhaustive new schedule. Set a time that you want to wake up every day (for me it is 7:00 AM), and set multiple alarms. Get up
every single day at your set time, no exceptions. You will be tired and groggy for a week or two as you will find yourself going many nights with very little sleep at first. But I promise, after a few weeks when your body starts to adjust, it will really help you in the long run.
I used the above method maybe 7-8 months ago, as I was staying up until 5 or 6AM every night and sleeping in until the evening. It was ridiculous. Now, for the last 7 months I've been waking up every day at 7:00 AM and I don't even need an alarm anymore

My internal clock has just adjusted to waking up at this time every day, and as a result, I am usually finding myself getting sleepy around 10 PM onwards. It feels great to have nice long, full days again, and to get up early as the sun comes up every morning and drink my coffee
