Apple PowerBook (Duo, 2300 Series) - Manual (Page 27)

Putting the computer to sleep
Sleep is a power conservation feature of Macintosh PowerBook computers
that reduces the amount of power the computer draws when it’s not being
used. When the computer is in sleep, it has a darkened screen and appears to
be off. A small green light flashes on the top of the display case when the
computer is in sleep. (Note: The computer must be on in order for you to put
it to sleep.)
To put the computer to sleep, do this:
1 Press and hold the Power key for about two seconds.
2 Click the Sleep button.
WARNING Once you put your computer to sleep, listen for the hard disk
to stop spinning before you transport your Macintosh PowerBook.
Transporting your Macintosh PowerBook with the hard disk spinning
can damage your computer.
Sleep indicator
17 Getting Started