[header] How to be nocturnal [title] Train yourself gradually. [step] It's difficult to switch straight from a normal sun-driven schedule to one in which you're sleeping while the rest of the world is awake. Doing this will likely just leave you completely sleep deprived, since you'll force yourself to stay up all night and you won't be able to sleep well during the day. 
Instead, gradually start staying up later each night and sleeping in later in the morning. Push the times back more and more, and in a week or so you won't have as much trouble waking and sleeping when you want to.