No one's stopping you.
Just somethings to keep in mind:
1. Power - Might seem obvious, but make sure it's plugged in. Taking the battery out insn't a bad idea either.
2. Sleep settings - You might have laptop power saving features, turn them off so it doesn't sleep 6 hours into it.
3. Cooling - Keep your machine cool, don't leave it in the sun or on a bed.
Otherwise, your ibook is like any other mac and will have a grand old time alone at home, gossiping with all your other electronics.