untamedhysteria said:it's because of power spikes happening inside the computer...the motherboard is still on in sleep (basically, the only thing left on) therefor it doesn't need a jolt of electricity to start up again, as it would with it being completely off.
Call me crazy, but the mechanical items, such as hard drives, would have more of an impact of lifespan due to turning off and on than electrical (solid-state) items. I've never heard of a motherboard being worn out due to power cycles. This is equivalent of saying the RAM will wear out by power cycling the machine.