Most of my advice comes from a more holistic approach than modern medicine.
Are you familiar with Seratonin and melatonin? Seratonin is responsible for mood and how 'awake' you feel. During the day, a healthy person's seratonin is at a fairly high level. As the day wears on, melatonin levels rise. It is melatonin that allows us to sleep.
It would seem these two chemicals are out of balance for you at the moment. So you need to get your lifestyle back 'into' balance and your hormones should hopefully follow suit.
Spending all your recreation time at the computer is probably not good for you. Perhaps going for a walk, doing exercise, doing OTHER THINGS will help. Exercise is very handy - I used to have some trouble getting to sleep(would lie in bed for a good hour or two before sleeping), but when I started doing exercise 2-3x/week, within a few weeks i was sleeping like a log.
Diet is important too. Healthy meals are good.

Try to limit your carbs in the evening - these are our main source of energy. So chocolate, sweets, bread, pasta, rice, potatoes... for a good few hours before bed try not to eat any of these. A glass of milk is handy too.
Oh - herbal teas! There is valerian, but you are supposed to cycle it 3 weeks on/1 week off. I don't have personal experience with it but I hear good things. Rooibos/Red b-ush tea is great! Its full of antioxidants, 50 times the potency of green tea, and 10 times the cancer fighting properties. Its very healthy, and is naturally caffeine-free. I find it helps to allow for restful sleep if brewing a cup for bed.
I hear some great things of Banisteros Caapi tea, too. Although in higher doses when combined with other plants it forms a 'drug' - I hate that term - that combination of plants is seen more as a sacred healer. On its own, it is perfectly healthy. In small doses, it greatly balances out seratonin and melatonin by using up seratonin receptors or somesuch (Im not familiar with the science) - everyone i know who has used this for sleeping disorders says it has lulled them into greatly restful sleep, and they awake feeling refreshed.
Oh yeah, having a warm bath or shower before bed helps too. The warmth will relax your muscles.
Some breathing exercises before bed would help both your lungs and help relax your body and mind for sleep. Breathing slow, deep breaths, maintaining your focus on the sensation of breath in and out of your nostrils is a great medicine for all sorts of stress.
And DONT think about trying to get to sleep while you are in bed. This is a horrible thought pattern than will ensure you feel irritated and unable to sleep. If you find yourself worrying, go back to the breath. or read a book/listen to relaxing music. Take your mind off the incessent thoughts of "OH FFS I AM NOT ASLEEP YET."
Best of luck man.

good dreams!