I know many of my friends and family either leave their computer on when they go to bed or put it in sleep mode. I know that keeping the computer on or putting it in sleep mode uses energy for no reason. You will cut down on your electric bill and help save the earth by shutting down, but more importantly, your mind will sleep easier at night.
Here is my theory on this. The computer and personal devices have taken over our lives, but we must mentally be able to separate ourselves from technology. At night, if you normally keep your computer on or put it in sleep mode, you are also mentally not shutting down.
I think we must shut down our electronics so that subliminally our minds understand that the day is over. This will help us rest easier and sleep better because our minds will not in sleep mode, but rather they will be fully shut down, and thus, can be fully restored with while sleeping.