Many years ago, I practiced myself to sleep less. I started from 8 hours a day. I keep reducing til I reached 5 hours a day. I had to drink a lot of water during the day. I occasionally had fever when I tried to sleep less than 5 hours or when I didn't drink enough water.
I tried to sleep less because I believe that we gain experience and memory only when I wake up. Sleeping seems like a waste of time to me at the moment.
Many years had passed. I seems to gain more experience than people at my age. I believe my hard working had paid off. However, as @Zonata has mentioned, sleepless comes with its cost. I started to lose my hair.
So I shaved my hair or wear skin-head cut. :)
I didn't regret my actions. I am aware that I'm over-using (almost abusing) my body. But I don't know if I would have a chance to get old and use it many years from now. Again, I decided to choose more time today and I would accept the consequences even if that means torturing days when I get old.
In sum, the answer is you can. With practice and a lot of water, you can sleep few hours a day. Spending half an hour exercise + 5 hours sleep can make you feel fresher than 6 hours sleep (and you gained 30 minutes bonus in this case). But don't forget that you have only 1 body that you have to stick to for the rest of your life. Make sure you do not regret your decision.
You might want to search for sleeping techniques such as uberman sleep (sleeping in short periods spreading across the day) or mobile apps which wake you up when you are not in deep sleep (you feel drowsy and tired when wake up while you are in deep sleep).
Wish you made the choice that you won't regret! Good luck! :)