Falling asleep at an illuminated reticule eyepiece can be very counter-productive and just takes the fun out of astrophotography. Most of us are pre-disposed to sleep at certain times of the day and the human body-clock often does not agree with the hours required for this pass-time.
That's where autoguiding comes to the rescue. Simply put, it is some sort of video camera, attatched to a second telescope that paralells the imaging telescope. This removes the need for constant scrutiny and manual correction by the user. I use a Phillips ToUCam or an Orion Starshoot Autoguider, both of which are effective. (See photo's below)
While the main telescope and imaging device is capturing light from distant stars, a star somewhere near or in the field of view is chosen as a guide star. This guide star is centred and detected by the second telescope and autoguide camera.

Using a software program like PHD guiding, this is displayed on-screen of a PC monitor.
With a simple click, you can designate a star and tell the camera to lock on it. The camera plugs into the mount of the telescope (mine is an EQ6) and communicates directly with the mount. After a simple calibration performed by the sortware, the camera then takes up the task of sending corrections to the mount to keep the star on a particular set of pixels.
Once it is off and running, you are free to commence your long exposure with your other camera and telescope and go have a cuppa.