Friends MBP makes noise during sleep?

[rye9]

My roommate's MBP (last generation or 2 generations ago I believe... not the present)... overnight while it is asleep makes an occasional noise every 20 minutes or so... idk if it's the optical drive or the HDD. Anyone know what this is and why?

 

[Theclamshell]

is it snoring

 

[mrsir2009]

So does my iMac and my Dad's MBP. Its the HD revving every so often, don't know why but it does that.

You should turn your computer off at night anyway, its not too good for your MBP. And then there's electric radiation, which comes from things like computers being turned on all night, its not good for you either...