You would be surprised what could be running the background.
You need to go to "Start" and then in the search box type "msconfig" (without the quote marks). Next click on the "Startup" tab and see what is listed as running. Do not uncheck anything there that you don't know what it is before doing some research online. Doing so could cause you way more problems. Once you have unchecked what you want/can, then reboot. Once you have done what you want and put the laptop to sleep again, see how long the battery lasts.
Also, make sure the display is turning off when you put it to sleep and close it. If the display stays on (which can happen) then it will drain the battery faster.
Lastly, you may want to check the power settings for when sleeping. Go into "Control Panel" and then "Power Options". Click on "Change plan settings" next to whatever plan you are using and then on the next screen click "Change advanced power settings". Go through the list and make sure that all options are set to do what you want, and to use less power, when sleeping.