HD noise when I open my notebook

This is a minor problem but I'm wondering if there is anyway to stop the HD noise whenever I open my MBP. It sounds like the HD is spinning or something whenever I open my notebook. Sorry if my explanation stinks.

I'm just wondering because I think it might be distracting whenever I open my notebook in class.

That's not your hard drive spinning, it's your optical drive. When you close the lid on your Macbook it goes to sleep. Not sure why it needs to spin up the optical drive when it returns from sleep, but that's just how Macs work.

Trust me, it's really not as loud as you think it is.