I've got a laptop charger with a blue led. It's awful, I have to remember to unplug it at night, even in the other room. I've forgotten before and woke up to use the washroom only to find the whole living room lit up from the little led and I'd feel instantly wide awake.

Contrast that with a USB charger I picked up in an emergency, unaware it had a red led that was on constantly as long as the cord was receiving power, fucking terrible design and I've thankfully replaced it, but it didn't bother me too badly when I had to use it in my room at night. I could still sleep and everything.