First line of the abstract: Ambient light can influence sleep structure and timing.
So of course the eye mask isn't necessary at all, reducing the ambient light is the key. Mask is one option, but black out curtains (in most areas) and eliminated or shielding any light emitting devices in the room is key.
It's incredible how bright a room can be with the lights off in the dead of night.
I use small strips of electrical tape to block led lights from small appliances I keep in my bedroom. I wish more companies were thoughtful in reducing the amount of light their electronics emit in a default state.
So of course the eye mask isn't necessary at all, reducing the ambient light is the key. Mask is one option, but black out curtains (in most areas) and eliminated or shielding any light emitting devices in the room is key.