Apple Wireless Keyboard & Mouse Issue

Hello,

I have a problem with my Apple Wireless Keyboard & Mouse disconnected while the computer is sleeping. For example, when the computer goes to sleep, and I want to press the spacebar or click the mouse to wake up the Mac, it does not turn on. I instead have to press the power button of the mac to wake the mac from sleep then hold the power button on the keyboard, and click the mouse for several seconds before the mouse and keyboard decide to reconnect.

I have a iMac 27-inch Late 2009 with a 3.06GHz Intel Core 2 Duo processor, 4GB memory, ATI Radeon HD 256MB graphics if that helps at all.