“This”! Black gaffers tape. Leaves no glue residue. One roll should last you a very long time. I have kept a roll in my suitcase for years. Learned that trick when I had to travel for work and live out of hotels. Hotels have so many offending lights in a small area: TV, Thermostat, lights on the air condition unit, refrigerator, alarm clock, fire alarm, etc.
Hands down, without a 2nd thought.