Macbook Air closed and pretty warm?

I've only had my MacBook Air for a few weeks now, and I really hadn't noticed this before, but I'll leave the screen up, and it goes to sleep, but I'll come back and pick it up, and it seems pretty warm to me. This is hours later btw. So, I tried closing the lid, and not shutting down the OS, and I came home this evening and it was very warm again? I have Safari, iTunes, and mail running. I have two hard drives connected to my Airport Extreme. I can't think of what might make this happen, because I swear, it was staying extremely cool in the past when waking it from sleep. Any input is appreciated!

Terry

GGJstudios said:

It sounds like it may not have remained in sleep mode. For sleep issues, you may find some useful ideas here:

• Determine why your Mac wakes up from sleep
• OS X Mountain Lion: If your Mac won’t go to or stay in sleep
• Mac OS X: Why your Mac might not sleep or stay in sleep mode
• One sleep problem caused by printers - solved ... and another
• If your Mac isn't sleeping properly and you have gfxCardStatus installed, try uninstalling it.

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Thanks, I will read all of these and see what I can come up with. It seems that the system is asleep, because the only way I can wake it is by pressing a key like the spacebar, but who knows....

inselstudent said:

I think it's the new power nap feature introduced with 10.8 which keeps your Mac up to date even while sleeping. It syncs your mail, iCloud stuff and whatnot afaik. You can turn it off or configure it in Settings->Energy saver (I think that's what it's called, it has a light bulb icon)

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I'm going to try and turn it off and see if that helps any. Just have to keep trying new things to see.. Thanks!