Under energy saver there is the hard drive sleep option (the tick box). I started using it, but recently I find that my hard drive keeps powering down alot more often than I expected they would- ie. pause itunes for 10mins and its gone to sleep, press play again and it takes 2-3s for the HDD to power back up first before resuming. Clearly this normal behaviour, just more frequent that I expected. However I am worried that my HDD's will die alot sooner with all the additional powering up and down they do, outside of the booting up/reboot cycles in my own day-to-day use. The common belief is that HDD's fail more often if you continually power them up and down compared to having them spinning all the time (usage rates being the same). Should I be worried? NB. is there anyway to change the time before the HDD's go to sleep? There isn't an option in OS X afaik, just the tick box?