Here are my tips of items to bring when travelling when night bus:
-A neck pillow (preferably one with a hook that you can clip on to the backpack).
-An eye mask (I can never sleep when I see a lot of lights on and when the sun comes up. A mask helps immensely).
-A Kindle or book. (On my most recent night bus ride I alternated between reading Lord of the Rings and a non-fiction book about ancient Babylon under the reign of Nebuchadnezzar).
-A reading light (This way you won't keep everyone else up if all you want to do at 2 AM is read about ancient Babylon).
-Other electronic devices (Like phones or laptops and Kindles for said electronic devices).
-A really good travel-themed playlist (I still associate certain songs with certain trips).
I highly recommend travel by night bus at least once!