I’ve never been an eye mask or ear plug wearer (except on motorcycle journeys), but I have to say they have countless value on a backpacking odyssey.
You simply must take them, and you simply must try them. The eye 
mask blocks overhead lights on airplanes, and the golden rays of Thai sunshine allowing you to sleep into midday after say a ‘Big Night in Patong Beach‘.
The earplugs mute out the babble of hair hostesses, the hum of air-conditioning, even the chanting and drumming of Bangkok rioters!
Watch out you might get addicted to using them like me!
Oh I am. It does make waking up difficult though.