Rude - no, your seatmate may be on a completely different time zone and reading should be considered an unobtrusive activity.

Disruptive to sleep - maybe, but it's incumbent to those sensitive to bring an eyemask. Certainly much less disruptive than someone reading a paperback with the overhead light or FAs with 200 lumen LED lights clipped to their lapel aimed at eye level offering you an apple at 3 am.