How can I stop my iPhone 4 from freezing and turning off by itself?

3 days ago, my phone started freezing very often. I would hold the sleep and home button for 6 seconds to restart it. After a while, it started turning off and on by itself. Just last night it had this lit up black screen. It was totally upresponsive and my iPhone did not show up in iTunes. I let the batter run out and than I charged it. It was fine for a couple of hours and than it started turning of and on by itself. It worsened to the point where right away when my iPhone 4 turned on, it turned off. Now it has a blue screen. Pressing the home and sleep button doesn't hel. It doesn't show up in iTunes either. Should I wait for it to run out of battery like last time? What can I do in the future to prevent my phone from freezing and turning off. Will upgrading it to the newest operating system help? This phone is nearly a year and a half old. Please help.