These are two steps for calibrating your macbook as stated by apple. "Continue to keep your computer on until it goes to sleep. Save all your work and close all applications when the battery gets very low, before the computer goes to sleep. Turn off the computer or allow it to sleep for five hours or more." My question is, the first sentence tells me to keep the computer on until it goes to sleep. then the final sentence says i can either let it sleep or turn it off? which is better for optimal battery performance? once it runs down im unsure of what to do...turn it off..or leave it in sleep mode all night?